fix(desktop): localize the native file and save dialog titles

[orangeCatDeveloper]

Summary

The native open and save panels carried English titles in every locale. A zh user picking a reference folder, adding attachments, importing a Skill or a pet, or saving a conversation read the one English string on an otherwise translated screen. All Files was the worst of the set: the file-type dropdown lists it directly beside the OS's own localized entries, so the panel reads half-translated.

Seven strings move into native-file-dialog-copy.ts, a typed UiCatalog beside the existing project-picker-copy.ts. Two call sites (markdown-save-ipc-main.ts, pet-pack-import.ts) and runtime-host-skills-ipc-main.ts gain a resolveLocale dependency, the form createPermissionOverlayMain already uses; the lower-level markdown-save-main.ts still takes a plain string, so nothing below the IPC boundary starts depending on a catalog.

Format names stay in English on purpose: Markdown, Skill Markdown and PNG and JPEG identify a file format, not a product concept, and translating them would add noise rather than clarity.

This also deletes runtime-host-boot-copy.ts — 90 lines of trilingual catalog whose only importer was its own test. The live copy for that surface is native-diagnostic-dialog-copy.ts.

Refs #2672

Verification

apps/desktop full dist suite        2463 pass / 5 fail
apps/desktop typecheck (4)          0 errors
check-locale-hygiene                passed
npm run format:check                clean

The five failures are browser-message-box, red on the unmodified base (7 tests, 5 fail), unrelated to this diff.

The new test asserts every key differs from its English value and carries Han text in both Chinese locales, so a forgotten translation fails rather than silently shipping English.

Review focus

dialog.title is honoured on Windows and Linux; macOS does not render it on the native panel. The change is still correct there — All Files appears in the file-type dropdown on all three platforms — but a macOS screenshot would not show the titles.

main.ts's showErrorBox('Maka Dev', …) is deliberately untouched: it is the catch-path fallback for a development-only single-instance dialog whose main path already resolves the system locale through DEV_SINGLETON_COPY.

AI use

Select exactly one:

• No generative tool made a substantive contribution
• Generative tooling made a substantive contribution

Tool(s) and scope: Claude Code — located the untranslated sites, wrote the catalog and the locale plumbing, the test, and this description. The zh-CN/zh-TW wording and the decision to leave format names in English were the contributor's. The commit carries a Generated-by: Claude Code trailer.

Checklist

• Tests cover the change and fail without it
• Lint, format, typecheck and the affected suites pass locally

Does this PR entail a change in behavior?

• Yes — six dialog titles and the All Files filter label now follow the Desktop locale
• No

[me2seeks]

PR 5179 Review

结论

APPROVE
七个 native 对话框标题/过滤器名移入带类型的 nativeFileDialogCopy 目录，三个 register 函数获得与 createPermissionOverlayMain 同形的 resolveLocale 依赖；删除的 runtime-host-boot-copy.ts 确无生产引用。

发现

无

不确定性（不发到 GitHub 的疑虑）

• 新增测试 native-file-dialog-copy.test.ts 断言 zh-CN/zh-TW 每个字符串"与 en 不同且含汉字"。对 importSkillSource（含 "Skill" 拉丁词）这类键，"与 en 不同"在 zh 翻译恰好等于英文时会误报，但当前三个 locale 值均不同，测试通过；属测试健壮性偏好，不发。
• app-icon-ipc.ts:179 的 showOpenDialog 仍无 title（走 OS 默认），PR 声称覆盖"否则翻译界面上的一个英文字符串"——OS 默认标题本身是本地化的，不算遗漏，故不发。
• runtime-host-boot-copy.ts 的文案已存在于 native-diagnostic-dialog-copy.ts（已确认 "Maka workspace needs repair" / "Keep Offline" 在后者中），删除是去重而非丢失；未逐字 diff 两处的完整 90 行对应，风险极低。

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✅ 对抗性审查（第一性原理 + 奥卡姆剃刀 + 证据核对）通过：未发现真实的 P0–P3 问题。@me2seeks 请把关是否 merge。