feat(feedback): in-app user feedback with admin review and account roles

User-facing Feedback screen (Settings -> Info, registered accounts only): a
message (<=1024 runes) plus one optional attachment, an anti-spam gate (one
unreviewed message at a time), and the operator's inline reply with a
Settings/Info badge. Server-rendered admin console section (/_gm/feedback):
unread/read/archived queue with per-user search, detail with read/reply/
archive/delete/delete-all, safe attachment serving (nosniff, images inline via
<img>, others download-only). Introduces account_roles, the first per-account
role table; feedback_banned blocks only feedback submission, granted/revoked
from /users and the delete-with-block action.

- migration 00004_feedback (feedback_messages + account_roles) + jetgen
- backend internal/feedback (store+service), internal/account/roles.go
- wire: FlatBuffers feedback.submit/get/unread; gateway guest gate (Op.NonGuest,
  is_guest via session resolve) -> guest_forbidden before any backend call
- reply push reuses NotificationEvent with a new admin_reply sub-kind
- UI: /feedback route + screen, attachment picker, badge, channel detection, i18n
- tests: feedback unit (Go+UI), gateway guest-gate, inttest lifecycle, e2e
- docs: PLAN stage 19, ARCHITECTURE s15, FUNCTIONAL(+ru), TESTING, READMEs

ui/src/lib/routeparse.ts

@@ -13,6 +13,7 @@ export type RouteName =
   | 'settings'
   | 'about'
   | 'friends'
+  | 'feedback'
   | 'stats'
   | 'notfound';
 
@@ -53,6 +54,8 @@ export function parse(hash: string): Route {
       return { name: 'about', params: {} };
     case 'friends':
       return { name: 'friends', params: {} };
+    case 'feedback':
+      return { name: 'feedback', params: {} };
     case 'stats':
       return { name: 'stats', params: {} };
     default: