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/app-iced/src/pages/appearance/section/panel.rs

@@ -2,28 +2,45 @@
 
 use iced::Element;
 
+use unlucky_i18n::catalog::Key;
+use unlucky_i18n::Lang;
+
 use crate::app::components::inputs::{slider, Slider};
 use crate::pages::Message;
 use crate::theme::Ui;
 
-use super::super::alpha::{panel_alpha_from_fraction, panel_fraction};
+use super::super::alpha::{panel_alpha_from_fraction, panel_fraction, PANEL_ALPHA_FLOOR};
 use super::super::state::State;
 use super::super::Change;
-use super::slider_row;
+use super::{fixed2, slider_row, t, tr};
 
 /// 把 ③ 面板透明度推进 `rows`。
-pub(super) fn push<'a>(ui: &'a Ui, state: &'a State, rows: &mut Vec<Element<'a, Message>>) {
+pub(super) fn push<'a>(
+    ui: &'a Ui,
+    state: &'a State,
+    lang: Lang,
+    rows: &mut Vec<Element<'a, Message>>,
+) {
     // ③ 面板透明度（CPU 档强制 1.0）
     let forced = state.panel_is_forced();
     let panel_percent = if forced {
-        format!("100% (forced from {:.2})", state.panel_alpha)
+        // 数值占位：`{requested}` 是请求值（词表不认 `{:.2}`，所以在这里先格式化成两位小数）。
+        tr(
+            lang,
+            Key::SettingsAppearancePanelOpacityForcedValue,
+            &[("requested", &fixed2(state.panel_alpha))],
+        )
     } else {
         format!("{:.0}%", state.effective_panel_alpha() * 100.0)
     };
     let panel_hint = if forced {
-        "Software renderer: panels stay fully opaque (window transparency still works)."
+        t(Key::SettingsAppearancePanelOpacityForcedHint, lang).to_owned()
     } else {
-        "Only the panel/card layer. Floor 0.40; independent of window transparency."
+        tr(
+            lang,
+            Key::SettingsAppearancePanelOpacityHint,
+            &[("floor", &fixed2(PANEL_ALPHA_FLOOR))],
+        )
     };
     let panel_control = if forced {
         slider(Slider::new(ui, panel_fraction(1.0)))
@@ -36,9 +53,9 @@ pub(super) fn push<'a>(ui: &'a Ui, state: &'a State, rows: &mut Vec<Element<'a,
     };
     rows.push(slider_row(
         ui,
-        "Panel transparency",
+        t(Key::SettingsAppearancePanelOpacity, lang),
         panel_percent,
-        panel_hint.to_owned(),
+        panel_hint,
         !forced,
         panel_control,
     ));