feat(saves): 实例存档 / 截图的只读列表与打开文件夹（M235 STOREMVP）

用户诉求是 PCL 差距四项里的「存档截图 / 导入」，M230 审计确认三层全缺。塔裁决 U3
把这一版钉成「只读列表 + 打开文件夹」，不做缩略图墙（缩略图要引图片解码依赖，而
AGENTS §2 只允许 palette-extract 引 image 类依赖；截图/导入产物形态也没定型）。

core
- `game::saves`（新）：只读列 `<run_dir>/saves`（世界目录）与 `<run_dir>/screenshots`
  （图片文件）。只调 symlink_metadata / read_dir / metadata，不建目录、不写文件、不读
  文件内容（`icon.png` 只判存在）。目录不存在 ⇒ 空列表不是错误；存在但不可用（符号
  链接 / 不是目录 / 读不了）⇒ 具名错误。条目级异常逐条登记原因，不静默丢。
- `platform::opener`（新）：`open_dir` 是**目录**打开器的唯一收敛点（explorer / open /
  xdg-open），内部复用 `child::quiet`，cfg 分支只此一处。塔明确要求按 AGENTS §6 放
  platform 而不是业务模块，并要一条可执行判据防退化
  （`the_launcher_literals_live_here_only` 扫 `crates/core/src`：除本文件外不许出现
  `"explorer"` / `"xdg-open"` 字面量）。

presenter
- `dto::saves`：SavesCommand（List / OpenFolder）、SavesListView、SavesFailureView
  （结构 + OS 原文，不拼中文）、`SavesListView` 的计数助手。
- `host::saves`：走 `job::spawn`，UI 只收快照；运行目录仍是
  `isolation::derive_game_dir` 的同一个答案（与启动 / mod 列表同源，**不写盘**）。
  「打开文件夹」打开哪个目录由 host 定：`saves/` → `screenshots/` → 运行目录。
  失败分三类（InstanceUnavailable / DirUnusable / OpenFailed），可重试。
- `state::saves`：快照整体替换、迟到结果丢弃、失败保留绑定（重试才有意义）。
- 接线：CoreEvent::Saves / AppCommand::Saves / HostTask::Saves。

app-iced
- `pages::instances::saves`：详情页 SAVES 卡片（MODS 之后、启动参数之前；**不套第二层
  滚动条**，整列那一条是唯一入口）。世界行带 UTC 时间与「有图标」，截图行带大小与时间；
  第一行固定画「这一版只读」（U3 边界让用户看得见）。读盘失败画一条红字 + 「重试」；
  打开文件夹失败**不画**重试（那个动作的重试就是再点一次按钮）。
- 接线：Message::{ReloadSaves, OpenSavesFolder}、`sync_saves`（与 `sync_mods` 同一判据）、
  Model::saves、`saves_shot` 出图夹具（ULL_SAVES_FIXTURE=1）。

i18n
- `InstancesSaves*` 20 条中英成对，catalog 与金表在**同一条锚点**后追加、逐字节一致。

证据
- core 只读判据：`game::saves::tests` 在真盘建世界/截图，调用前后各拍一次
  （相对路径, 是否目录, 字节数, mtime）指纹并逐条比对；另有用例钉「目录缺失不建目录」。
- presenter：`host::saves::tests` 真盘端到端（custom 档位派生运行目录 → 快照）。
- GUI：`--software-renderer` 1180×760 浅/深各一张 + 1180×1280 两张「整块卡片可见」
  （1180×760 下 SAVES 卡片位于折叠线附近，只能看到卡头；第二对用 ULL_WINDOW_SIZE
  把窗口拉高，口径与 M98 的矩阵一致），落 `DevDocs/artifacts/M235/`。

没做的（U3 边界内，见 handoff）：缩略图墙、导入、删除/重命名、`level.dat` 的
LevelName 解析（世界名暂时就是目录名）。

crates/i18n/src/catalog/golden.rs

@@ -105,6 +105,26 @@ pub(super) const GOLDEN: &[(&str, &str, &str)] = &[
     ("InstancesModsReasonNotFile", "that is not a regular file", "那不是普通文件"),
     ("InstancesModsReasonCollision", "a file with that name already exists", "同名文件已存在"),
     ("InstancesModsReasonRename", "the rename failed", "改名失败"),
+    ("InstancesSavesTitle", "SAVES", "存档"),
+    ("InstancesSavesReadOnly", "Read-only in this version: nothing here is moved or deleted.", "这一版只读：这里不移动、也不删除任何东西。"),
+    ("InstancesSavesCount", "{worlds} worlds · {shots} screenshots", "{worlds} 个世界 · {shots} 张截图"),
+    ("InstancesSavesLoading", "Reading saves/…", "正在读取 saves/…"),
+    ("InstancesSavesEmpty", "No worlds or screenshots yet — play once and they show up here.", "还没有世界或截图——玩一次就会出现在这里。"),
+    ("InstancesSavesMissingDir", "This instance has no saves/ or screenshots/ directory yet.", "这个实例还没有 saves/ 或 screenshots/ 目录。"),
+    ("InstancesSavesWorlds", "WORLDS", "世界"),
+    ("InstancesSavesScreenshots", "SCREENSHOTS", "截图"),
+    ("InstancesSavesNoWorlds", "No worlds yet.", "还没有世界。"),
+    ("InstancesSavesNoScreenshots", "No screenshots yet.", "还没有截图。"),
+    ("InstancesSavesWorldIcon", "has icon", "有图标"),
+    ("InstancesSavesTimeUnknown", "time unknown", "时间未知"),
+    ("InstancesSavesSkipped", "{count} entries skipped", "跳过 {count} 项"),
+    ("InstancesSavesOpenFolder", "Open saves folder", "打开存档文件夹"),
+    ("InstancesSavesRetry", "Retry", "重试"),
+    ("InstancesSavesFailed", "Could not read saves/: {reason}", "读取 saves/ 失败：{reason}"),
+    ("InstancesSavesOpenFailed", "Could not open the folder: {reason}", "打开文件夹失败：{reason}"),
+    ("InstancesSavesReasonDir", "the directory is not usable", "目录不可用"),
+    ("InstancesSavesReasonInstance", "the instance is gone", "实例已不存在"),
+    ("InstancesSavesReasonOpen", "the file manager did not start", "文件管理器没起来"),
 ];
 
 /// 金表的**全量**行（本文件 → [`tail`] → [`tail_ai`] → [`tail2`]，顺序即 `Key::ALL`）。

crates/i18n/src/catalog/instances.rs

@@ -154,6 +154,30 @@ macro_rules! instances_entries {
             InstancesModsReasonNotFile => ("that is not a regular file", "那不是普通文件"),
             InstancesModsReasonCollision => ("a file with that name already exists", "同名文件已存在"),
             InstancesModsReasonRename => ("the rename failed", "改名失败"),
+            // ── 存档区（M235 · STOREMVP）：**只读**列 `saves/` 与 `screenshots/` + 打开文件夹。
+            // U3 的边界写在 `InstancesSavesReadOnly` 里，页面固定画出来——用户点开就看见
+            // 「这一版只读」，不会以为漏了删除按钮。`saves/` / `screenshots/` 是**目录名**，
+            // 两套语言都原样保留（与 MODS 区的 `mods` 同一条口径）。
+            InstancesSavesTitle => ("SAVES", "存档"),
+            InstancesSavesReadOnly => ("Read-only in this version: nothing here is moved or deleted.", "这一版只读：这里不移动、也不删除任何东西。"),
+            InstancesSavesCount => ("{worlds} worlds · {shots} screenshots", "{worlds} 个世界 · {shots} 张截图"),
+            InstancesSavesLoading => ("Reading saves/…", "正在读取 saves/…"),
+            InstancesSavesEmpty => ("No worlds or screenshots yet — play once and they show up here.", "还没有世界或截图——玩一次就会出现在这里。"),
+            InstancesSavesMissingDir => ("This instance has no saves/ or screenshots/ directory yet.", "这个实例还没有 saves/ 或 screenshots/ 目录。"),
+            InstancesSavesWorlds => ("WORLDS", "世界"),
+            InstancesSavesScreenshots => ("SCREENSHOTS", "截图"),
+            InstancesSavesNoWorlds => ("No worlds yet.", "还没有世界。"),
+            InstancesSavesNoScreenshots => ("No screenshots yet.", "还没有截图。"),
+            InstancesSavesWorldIcon => ("has icon", "有图标"),
+            InstancesSavesTimeUnknown => ("time unknown", "时间未知"),
+            InstancesSavesSkipped => ("{count} entries skipped", "跳过 {count} 项"),
+            InstancesSavesOpenFolder => ("Open saves folder", "打开存档文件夹"),
+            InstancesSavesRetry => ("Retry", "重试"),
+            InstancesSavesFailed => ("Could not read saves/: {reason}", "读取 saves/ 失败：{reason}"),
+            InstancesSavesOpenFailed => ("Could not open the folder: {reason}", "打开文件夹失败：{reason}"),
+            InstancesSavesReasonDir => ("the directory is not usable", "目录不可用"),
+            InstancesSavesReasonInstance => ("the instance is gone", "实例已不存在"),
+            InstancesSavesReasonOpen => ("the file manager did not start", "文件管理器没起来"),
         } }
     };
 }