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/PlaylistTrackRow.test.ts

@@ -53,7 +53,7 @@ const removed: PlaylistTrack = {
   stream_url: null
 };
 
-// Missing file (#2527): the track row still exists — ids intact, history
+// Missing file: the track row still exists — ids intact, history
 // intact — but the server withholds the stream URL because the bytes are
 // not on disk. Deliberately distinct from `removed` above.
 const missingFile: PlaylistTrack = {