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/AcquisitionServiceRow.svelte

@@ -13,7 +13,7 @@
   import { errCode, errMessage } from '#lib/api/errors.js';
   import { pushToast } from '#lib/stores/toast.svelte.js';
 
-  // One indexer or download client (M502 #5518). The form is a copy of the
+  // One indexer or download client. The form is a copy of the
   // saved row, so Save is only offered when something changed. Secrets are
   // write-only: the server says whether one is set and never what it is.