perf: load the Settings dialog on demand; entry chunk 351.8 → 277.1 kB gzip

Settings (every page, pickers, the denoise tester) was in the entry
chunk though it only renders when opened. Load it lazily behind a
focusable spinner (it opens inside a FocusTrap), and warm the chunk
when the app goes idle. SettingsPages and the status localStorage keys
move to tiny modules so callers don't pull the dialog back in.
sanitize-html (+postcss, htmlparser2) and chroma-js get their own vendor
chunks; with Settings gone the chunk graph had dropped them into the
entry chunk.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/features/settings/pages.ts

@@ -0,0 +1,11 @@
+/** Settings dialog pages. Kept apart from Settings.tsx so callers can name a
+ * page without pulling the dialog into the entry chunk. */
+export enum SettingsPages {
+  GeneralPage,
+  AccountPage,
+  NotificationPage,
+  DevicesPage,
+  EmojisStickersPage,
+  DeveloperToolsPage,
+  AboutPage,
+}