chore: remove the bug-report integration

Drop the in-app bug-report surface end to end: the user submission page,
the feedback intake and admin inbox, the optional GitHub-issue
escalation, the operator config, and the dedicated achievement badges.

- delete the /bugreport page and the bugreport / feedback / admin-feedback API routes
- drop the Feedback model, its enums, and the AppSettings GitHub-issue and enable columns (migration 0205)
- remove the admin Feedback section, the Bug Report integration card, and the system-status row
- drop the bug-report nav entry and the app-settings provider that only carried its flag
- remove the bug-hunter achievement badges and their metric
- prune the related i18n keys across every locale and the encrypted-column and key-rotation registries

scripts/rotate-encryption-key.ts

@@ -227,11 +227,9 @@ async function main() {
 
   // ───── AppSettings — operator credentials (String) ─────
   // Columns: "adminAiKeyEncrypted" "webPushVapidPrivateKeyEncrypted"
-  // "githubIssueTokenEncrypted"
   for (const field of [
     "adminAiKeyEncrypted",
     "webPushVapidPrivateKeyEncrypted",
-    "githubIssueTokenEncrypted",
   ]) {
     results.push(
       await rotateStringColumn("AppSettings", field, prisma.appSettings),