Fix runtime startup/editor bugs and offline build surfaced by Playwright testing

[Copilot]

End‑to‑end Playwright testing of the JavaScript app (/src) surfaced a startup crash, a broken Code Editor, and build/console failures. This addresses those and adds the captured screenshots.

Fixes

• Start Menu init race — StartMenuController read the IndexedDB filesystem in its constructor, before fileSystem.init(), throwing Database not initialized. Building pinned tiles is now deferred to os.Ready().

• Code Editor — Monaco fetched its worker from unpkg.com/monaco-editor@latest, which breaks offline and can version‑mismatch the bundled Monaco. Now uses webpack‑bundled workers:

  getWorker(_id, label) {
    if (label === 'typescript' || label === 'javascript')
      return new Worker(new URL('monaco-editor/esm/vs/language/typescript/ts.worker.js', import.meta.url));
    // css/scss/less, html, json, and editor.worker handled likewise
    return new Worker(new URL('monaco-editor/esm/vs/editor/editor.worker.js', import.meta.url));
  }

• Offline build — main.less pulled Google Fonts via a build‑time @import url(...), failing the whole less-loader build offline. Moved to a runtime <link> in index.html.

• Startup error noise — ThemeManager.ensureThemesDirectory used stat() (which logs on miss) as an existence check; switched to exists().

• /favicon.ico 404 — added an inline SVG favicon.

• Blazor wasm2 build — removed a stray } in WindowStateTest.razor.cs.

Screenshots

Captured per‑app under docs/screenshots/ (README.md maps each image).

Notes

• Console messages for Google Fonts / xterm CSS remain only in fully offline runs and degrade gracefully.
• The wasm2 Blazor port is a WIP that does not fully compile; only the one stray syntax error is touched here.