[hot-YUser]

Summary

Add resource-based UI localization to the WinUI app and ship Traditional Chinese (zh-Hant) and Simplified Chinese (zh-Hans) alongside English.

• All interactive UI text now comes from Strings/<tag>/Resources.resw through a small Loc/{loc:Tr Key=…} seam. English remains the source language.
• Translate the main window, removal catalog, build/settings/review pages, notices, confirmation dialogs and the full cancel flow.
• Add a Language picker in the sidebar. The choice is stored in %LOCALAPPDATA%\Tiny11Builder\settings.json and applied after a restart; the notice offers Restart now.
• Add docs/translations.md describing the file layout, key rules and how to add another language.
• Add LocalizationTests: key parity across languages, non-empty values, matching {0} placeholders, XAML key coverage, and tag normalization (zh-TW → zh-Hant, zh-CN → zh-Hans).

Technical build-engine operation names, stage status words, the raw recipe and the build log remain English diagnostics; the interactive interface, removal catalog and user-facing notices are localized.

Why

Related to #651, #652 and #656. The app previously had no resource files at all: every string was hard-coded in XAML or C#.

Implementation notes

• The app is unpackaged, so MRT Core needs the PRI file at the default path. ProjectPriFileName is set to resources.pri; without it ResourceLoader does not find the app resources.
• ApplicationLanguages.PrimaryLanguageOverride is set before any XAML is parsed, so markup-extension text resolves in the selected language.
• Keys are flat with __ separators. MRT treats dots as resource-map separators, so a dotted key such as A.B cannot also be a parent of A.B.C.
• Adding a language is one copied Resources.resw file plus one LanguageCatalog entry; the tests enforce parity.

Verification

• dotnet build src/Tiny11Builder.App/Tiny11Builder.App.csproj -c Release: 0 warnings, 0 errors.
• Localization/app tests: 85 passed (LocalizationTests, AppFlowTests, AppChoiceTests, ProjectSupportTests, DeploymentTests).
• Full suite: 529 passed, 35 failed. The same 35 tests fail on a clean checkout of 8909da1 in this non-elevated environment (SeBackupPrivilege/DISM native tests); the three new localization tests are included in the 529 and no new failures were introduced.
• Manually verified both Chinese UIs render correctly, the language picker lists System default / English / 繁體中文 / 简体中文, selecting 简体中文 writes settings.json, and Restart now relaunches into the new language.

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摘要（繁體中文）

為 WinUI 應用程式加入以資源檔為基礎的介面在地化，並隨附英文、繁體中文（zh-Hant）與簡體中文（zh-Hans）。

• 介面文字集中於 Strings/<tag>/Resources.resw，透過 Loc 與 {loc:Tr Key=…} 解析；英文為來源語言。
• 翻譯主視窗、移除目錄、建置／設定／檢閱頁面、通知、確認對話框與完整取消流程。
• 側邊欄新增語言選擇器；選擇會寫入 %LOCALAPPDATA%\Tiny11Builder\settings.json，重新啟動後套用，通知列提供「立即重新啟動」。
• 新增 docs/translations.md 說明資源結構與新增語言流程。
• 新增 LocalizationTests：語言鍵一致性、非空值、{0} 佔位符一致、XAML 鍵覆蓋，以及語系標籤正規化。

建置引擎的操作名稱、階段狀態字、原始配方與建置記錄仍為英文技術診斷；互動介面、移除目錄與使用者可見通知均已翻譯。

驗證：Release 建置 0 警告 0 錯誤；相關測試 85 項全數通過；完整測試的 35 項失敗與未修改前的基準完全相同（此非提權環境缺少 SeBackupPrivilege／DISM），未新增失敗。實機確認兩種中文介面、語言選擇寫入設定，以及重新啟動後套用新語言。