docs: web comments say what the app does, not how it came to be (#6277)

Rewrites the web app's comments to rule 32. Task, milestone, rule and
spec ids are gone; regression stories are restated as the trap they
guard (public auth routes, the menu's stopPropagation, universal loads
under adapter-static, metric deltas with their margin). Flutter and
Tauri mentions now name the Android app or a native shell, operator
quotes and dates are dropped, and one library's counts no longer
appear outside test fixtures. Verified with a TypeScript-scanner token
comparison (template literals and regex literals re-scanned): only
comment text changed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

web/src/lib/components/FollowControl.svelte

@@ -12,7 +12,7 @@
   import { pushToast } from '#lib/stores/toast.svelte.js';
   import Modal from './Modal.svelte';
 
-  // Follow an artist for the wanted list (M502 #5520): their new releases are
+  // Follow an artist for the wanted list: their new releases are
   // wanted, filtered by a release-type profile. Admin-only; the artist page
   // shows it when the artist carries a MusicBrainz id.