feat(i18n): 外观页 40 条文案进词表（M180 I18NAPPEAR）

- 卡片内 22 处硬编码英文（整窗/面板透明度、背景图开关+路径、填充、暗化、配色来源）全部改走 Key
- 运行时诊断改成 key + 参数：`background::Note`（读盘/解码/过大/小图平铺）、`state::backend_note`、
  `palette::note` 全部返回 Key；`state.rs` 只留 key、不放文案表（390 → 391 行）
- 上限/下限常量走占位符 `{floor}` / `{max}` / `{limit}` / `{requested}`；`{:.2}` 在 Rust 侧格式化好
  再套模板（`Catalog::render` 只认 `{name}`）
- 新增 40 条 key（中英各一条），按装配链锚点插在 `SettingsAppearanceCornerSuspended` 之后，
  金表 `golden/tail.rs` 同位置插入 40 行（`rows() == len() == Key::ALL.len()`）
- 守卫三条：中文渲染全非 ASCII、卡片 key 全覆盖（改回写死英文即红）、外观 key 逐条真翻过
- probe 加第二条取证路（`record_rendered`），`take()` 签名不动（M179 的守卫在 scope 外）

crates/i18n/src/catalog/settings/appearance.rs

@@ -1,12 +1,38 @@
-//! 设置页「Appearance」分组文案（M116 首次落地：窗口圆角一档）。
+//! 设置页「Appearance」分组文案（M116 落了圆角一族；M180 `I18NAPPEAR` 补齐全组）。
 //!
 //! 加 key 时把条目写进 `$($acc)*` 后面即可（形状见 [`crate::catalog`] 的「域装配」一节）。
 //!
-//! ## 为什么只有圆角这一组的 key
+//! ## 两批 key：圆角（M116）在前，其余（M180）在后
 //!
-//! 本分组的既有控件（整窗/面板透明度、背景图、配色来源……）是 M93 落的，文案是英文基线字面量
-//! （`pages/appearance/section.rs`）。M116 新增的圆角档位**从一开始就走词表**（tower 口径：
-//! 设置项文案不许硬编码），所以这里先只有它这一组；老控件接词表归 i18n 接线 mission。
+//! M116 只落了圆角那 5 条；本分组其余控件（整窗/面板透明度、背景图、填充、暗化、配色来源）
+//! 是 M93 落的，文案一直是英文基线字面量。M172 审计量出这一页 27 处文案里 22 处硬编码、中文界面
+//! 本地化 0/27。M180 把**控件文案 + 运行时诊断 + 配色回落提示**全部搬进本文件：
+//!
+//! | 批次 | 条目 | 来源 |
+//! |---|---|---|
+//! | M116 | `Corner` … `CornerSuspended` | `pages/appearance/section/window.rs` 的圆角一段 |
+//! | M180 | `WindowOpacity` … `PaletteAdjusted` | 卡片各段标签/说明 + `state.rs` / `background.rs` / `palette.rs` 的诊断 prose |
+//!
+//! ## 为什么诊断也在这里（而不是留在 `state.rs`）
+//!
+//! `pages/appearance/state.rs` 已经 390 行、贴着 400 行硬线，放不下任何一张文案表。所以那一层只
+//! 给 **key + 已格式化好的参数**（`background::Note`），句子一律在本文件里。
+//!
+//! ## 数值参数：模板里只有 `{name}`，格式在 Rust 侧做
+//!
+//! [`crate::catalog::Catalog::render`] 只做 `{name}` → 值的字面替换，**不认** `{:.2}` 这类格式说明。
+//! 所以「位置/尺寸/上限」这些数字由调用方先 `format!("{:.2}")` 好再当参数传进来：
+//!
+//! | key | 原字面量 | 现在 |
+//! |---|---|---|
+//! | `SettingsAppearancePanelOpacityForcedValue` | `format!("100% (forced from {:.2})")` | `{requested}` = `format!("{:.2}")` |
+//! | `SettingsAppearanceWindowOpacityHint` | `Floor {:.2}` = `WINDOW_ALPHA_FLOOR` | `{floor}` |
+//! | `SettingsAppearancePanelOpacityHint` | `Floor 0.40` = `PANEL_ALPHA_FLOOR` | `{floor}` |
+//! | `SettingsAppearanceBgDimHint` | `Max 0.95` = `BG_DIM_MAX` | `{max}` |
+//! | `SettingsAppearanceBgTooLarge` | `(limit 8192 px per edge)` = `MAX_SOURCE_EDGE` | `{limit}` |
+//! | `SettingsAppearanceBgSmallTile` | `(max 64 tiles …)` = `MAX_TILES` | `{max}` |
+//!
+//! 常量走占位符而不是写进译文，是为了「改常量不用改两套译文」（M180 任务口径）。
 //!
 //! ## 文案口径（不许暗示所有平台一致）
 //!
@@ -28,8 +54,206 @@ macro_rules! settings_appearance_entries {
                 "Not in effect right now: window transparency is below 100%. Setting it back to 100% restores the rounded corners.",
                 "当前因整窗透明度不生效：把整窗透明度调回 100% 圆角即恢复。"
             ),
+            // ---- M180 `I18NAPPEAR`：卡片内文案（① 整窗 / ③ 面板 / ④~⑧ 背景图 / ⑨ 配色来源）
+            SettingsAppearanceWindowOpacity => ("Window transparency", "整窗透明度"),
+            SettingsAppearanceWindowOpacityHint => (
+                "Applies to the whole window. Floor {floor}; 1.00 = fully opaque.",
+                "作用于整个窗口。下限 {floor}；1.00 = 完全不透明。"
+            ),
+            SettingsAppearancePanelOpacity => ("Panel transparency", "面板透明度"),
+            SettingsAppearancePanelOpacityHint => (
+                "Only the panel/card layer. Floor {floor}; independent of window transparency.",
+                "只作用于面板 / 卡片这一层。下限 {floor}；与整窗透明度互不影响。"
+            ),
+            SettingsAppearancePanelOpacityForcedValue => (
+                "100% (forced from {requested})",
+                "100%（强制，原请求值 {requested}）"
+            ),
+            SettingsAppearancePanelOpacityForcedHint => (
+                "Software renderer: panels stay fully opaque (window transparency still works).",
+                "软件渲染：面板恒为不透明（整窗透明度仍然有效）。"
+            ),
+            SettingsAppearanceBackgroundImage => ("Background image", "背景图"),
+            SettingsAppearanceOff => ("Off", "关"),
+            SettingsAppearanceOn => ("On", "开"),
+            SettingsAppearanceImagePath => ("Image path", "图片路径"),
+            SettingsAppearancePaletteLevel => ("Colours: {level}", "配色：{level}"),
+            SettingsAppearanceBgFill => ("Fill", "填充方式"),
+            SettingsAppearanceBgFillCover => ("Cover", "铺满"),
+            SettingsAppearanceBgFillContain => ("Contain", "完整显示"),
+            SettingsAppearanceBgFillTile => ("Tile", "平铺"),
+            SettingsAppearanceBgDim => ("Dim", "暗化"),
+            SettingsAppearanceBgDimHint => (
+                "Blends the image toward the panel colour so text stays readable. Max {max}.",
+                "把背景图往面板底色上退，让文字读得清。上限 {max}。"
+            ),
+            SettingsAppearancePaletteSource => ("Colour source", "配色来源"),
+            SettingsAppearancePaletteBackground => ("Background", "取自背景图"),
+            SettingsAppearancePaletteWallpaper => ("Wallpaper", "取自壁纸"),
+            SettingsAppearancePalettePreset => ("Preset", "内置色卡"),
+            // ---- M180：运行时诊断（`state.rs` 的 backend_note + `background.rs` 的三种读盘失败 + 小图平铺）
+            SettingsAppearanceSoftwareRendererNote => (
+                "Software renderer: panel transparency and glass stay fully opaque (window transparency still works).",
+                "软件渲染：面板透明度与玻璃效果恒为不透明（整窗透明度仍然有效）。"
+            ),
+            SettingsAppearanceBgReadFailed => (
+                "Background image could not be read: {reason}",
+                "背景图读不出来：{reason}"
+            ),
+            SettingsAppearanceBgDecodeFailed => (
+                "Background image could not be decoded ({reason}; this build decodes PNG, JPEG and BMP)",
+                "背景图解不开（{reason}；这个构建只支持 PNG、JPEG 与 BMP）"
+            ),
+            SettingsAppearanceBgTooLarge => (
+                "Background image is too large to decode: {width}×{height} (limit {limit} px per edge)",
+                "背景图太大，解不开：{width}×{height}（每边上限 {limit} 像素）"
+            ),
+            SettingsAppearanceBgSmallTile => (
+                "Small image ({width}×{height}): tiles are scaled up so the window stays covered (max {max} tiles, no gaps).",
+                "图片很小（{width}×{height}）：图块会被放大，保证窗口铺满（最多 {max} 块，不留缝）。"
+            ),
+            // ---- M180：配色回落提示（`palette.rs` 把 design 的 `hint_key()` 翻成下面这些）
+            SettingsAppearancePaletteBgUndecodable => (
+                "Background image could not be read; colours fall back.",
+                "背景图读不出来，配色回落到下一级。"
+            ),
+            SettingsAppearancePaletteBgTooSmall => (
+                "Background image is too small to sample; colours fall back.",
+                "背景图太小，取不了色，配色回落到下一级。"
+            ),
+            SettingsAppearancePaletteBgBadDimensions => (
+                "Background image data looks inconsistent; colours fall back.",
+                "背景图数据前后不一致，配色回落到下一级。"
+            ),
+            SettingsAppearancePaletteBgNoOpaquePixels => (
+                "Background image is almost fully transparent; colours fall back.",
+                "背景图几乎全透明，配色回落到下一级。"
+            ),
+            SettingsAppearancePaletteBgLowChroma => (
+                "Background image is too monochrome to tint from; colours fall back.",
+                "背景图太单调（彩度不足），取不出配色，回落到下一级。"
+            ),
+            SettingsAppearancePaletteBgContrast => (
+                "Background image colours would be unreadable; colours fall back.",
+                "按背景图取的颜色读不清，配色回落到下一级。"
+            ),
+            SettingsAppearancePaletteWallpaperUndecodable => (
+                "Desktop wallpaper could not be read.",
+                "桌面壁纸读不出来。"
+            ),
+            SettingsAppearancePaletteWallpaperTooSmall => (
+                "Desktop wallpaper is too small to sample.",
+                "桌面壁纸太小，取不了色。"
+            ),
+            SettingsAppearancePaletteWallpaperBadDimensions => (
+                "Desktop wallpaper data looks inconsistent.",
+                "桌面壁纸数据前后不一致。"
+            ),
+            SettingsAppearancePaletteWallpaperNoOpaquePixels => (
+                "Desktop wallpaper is almost fully transparent.",
+                "桌面壁纸几乎全透明。"
+            ),
+            SettingsAppearancePaletteWallpaperLowChroma => (
+                "Desktop wallpaper is too monochrome to tint from.",
+                "桌面壁纸太单调（彩度不足），取不出配色。"
+            ),
+            SettingsAppearancePaletteWallpaperContrast => (
+                "Desktop wallpaper colours would be unreadable; colours fall back.",
+                "按桌面壁纸取的颜色读不清，配色回落到下一级。"
+            ),
+            SettingsAppearancePalettePresetContrast => (
+                "The built-in card needed a small contrast correction.",
+                "内置色卡做了一点对比度修正。"
+            ),
+            SettingsAppearancePaletteAdjusted => (
+                "A few colours were nudged for readability.",
+                "有几个颜色为了可读性做了微调。"
+            ),
         } }
     };
 }
 
 pub(crate) use settings_appearance_entries;
+
+#[cfg(test)]
+mod tests {
+    use crate::catalog::{placeholders, Catalog, Key};
+    use crate::Lang;
+
+    /// 本域的 key（`Key::ALL` 里按名字前缀筛；不手工列表，漏一条就少一条守卫）。
+    fn appearance_keys() -> Vec<Key> {
+        Key::ALL
+            .iter()
+            .copied()
+            .filter(|key| key.name().starts_with("SettingsAppearance"))
+            .collect()
+    }
+
+    /// 有没有汉字（与 `pages/settings/tests/appearance_section.rs` 的 `is_han` 同一段码位）。
+    fn is_han(ch: char) -> bool {
+        ('\u{4e00}'..='\u{9fff}').contains(&ch)
+    }
+
+    /// **M180 守门 ②**：外观分组的每条 key 都必须真翻过——英文照抄进中文表就地判红。
+    ///
+    /// 抓得住：① 新加 key 时中文栏直接抄英文（`chinese_catalog_is_actually_chinese` 也抓这条，
+    /// 但那条在 `catalog/tests.rs`、不属于本 mission 的 scope，而且不查「中文字里有没有汉字」）；
+    /// ② 中文译文变成纯 ASCII（比如只写了 `PNG` / `Preset` 这种专名）；③ 占位符集合两边不一致
+    /// （`{floor}` 只在一边有 ⇒ `render()` 吐出半截句子）。
+    /// 抓不住：译文翻得对不对（语义只能人审）。
+    ///
+    /// 变异证明：把任一条的第二个字符串换成第一个（`("Cover", "Cover")`）⇒ 本条立刻红（`assert_ne!`
+    /// 与 `is_han` 命中同一行）。
+    #[test]
+    fn every_appearance_key_is_translated_into_chinese() {
+        let keys = appearance_keys();
+        assert!(
+            keys.len() >= 40,
+            "外观分组至少 40 条 key（M180 落地时是 45 条），实际 {}：\
+             key 被搬走或前缀改名了？",
+            keys.len()
+        );
+
+        let en = Catalog::of(Lang::En);
+        let zh = Catalog::of(Lang::ZhCn);
+        for key in keys {
+            let (english, chinese) = (en.text(key), zh.text(key));
+            assert_ne!(english, chinese, "{} 的中文是英文照抄", key.name());
+            assert!(
+                chinese.chars().any(is_han),
+                "{} 的中文里一个汉字都没有：{chinese}",
+                key.name()
+            );
+            let mut left = placeholders(english);
+            let mut right = placeholders(chinese);
+            left.sort_unstable();
+            right.sort_unstable();
+            assert_eq!(left, right, "{} 的占位符两套译文不一致", key.name());
+        }
+    }
+
+    /// 数值参数必须走占位符，不许把常量写进译文（改常量时不该还要改两套译文）。
+    #[test]
+    fn numeric_limits_are_placeholders_not_text() {
+        let en = Catalog::of(Lang::En);
+        for (key, needle, placeholder) in [
+            (Key::SettingsAppearanceWindowOpacityHint, "0.08", "floor"),
+            (Key::SettingsAppearancePanelOpacityHint, "0.40", "floor"),
+            (Key::SettingsAppearanceBgDimHint, "0.95", "max"),
+            (Key::SettingsAppearanceBgTooLarge, "8192", "limit"),
+            (Key::SettingsAppearanceBgSmallTile, "64", "max"),
+        ] {
+            let text = en.text(key);
+            assert!(
+                !text.contains(needle),
+                "{} 把常量 {needle} 写死在译文里了（应当走 {{{placeholder}}}）",
+                key.name()
+            );
+            assert!(
+                placeholders(text).contains(&placeholder),
+                "{} 缺 {{{placeholder}}} 占位符：{text}",
+                key.name()
+            );
+        }
+    }
+}