Clarify changed and deleted files in the file viewer (#2670)

* fix(app): distinguish changed and deleted files

Successful reads now reconcile transient missing events without letting stale
cached data mask a deletion. File notices expose only actions valid for the
current buffer state.

* fix(app): preserve file state ordering

* fix(app): allow retrying file checks

* fix(app): clear unchanged file conflicts

* fix(app): keep file conflict recovery consistent

Own disk observation and read ordering in one model so stale reads and failed subscriptions cannot produce contradictory actions.

* fix(app): allow retrying file preview errors

Preserve daemon read errors and expose retry for initial and non-editable file loads.

packages/app/src/i18n/resources/zh-CN.ts

@@ -1472,7 +1472,9 @@ export const zhCN: TranslationResources = {
         cursor: "第 {{line}} 行，第 {{column}} 列",
         preview: "预览",
         source: "源代码",
-        unavailableTitle: "磁盘上的文件不可用",
+        deletedTitle: "文件已从磁盘删除",
+        checkFailedTitle: "无法检查磁盘上的文件",
+        preservedDescription: "打开的副本已保留。",
         conflictDescription: "本地内容已保留。请选择要保留的版本。",
         overwrite: "覆盖",
         reload: "重新加载",