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/client.ts

@@ -9,6 +9,7 @@ import type {
   BlockStatus,
   ChatMessage,
   EvalResult,
+  FeedbackState,
   FriendCode,
   GameList,
   GameView,
@@ -101,6 +102,14 @@ export interface GatewayClient {
   chatList(gameId: string): Promise<ChatMessage[]>;
   nudge(gameId: string): Promise<ChatMessage>;
 
+  // --- feedback ---
+  /** feedbackSubmit sends a feedback message with an optional single attachment. */
+  feedbackSubmit(body: string, attachment: Uint8Array | null, attachmentName: string, channel: string): Promise<void>;
+  /** feedbackGet returns the feedback screen state and marks any pending reply delivered. */
+  feedbackGet(): Promise<FeedbackState>;
+  /** feedbackUnread reports whether an operator reply awaits delivery (the badge). */
+  feedbackUnread(): Promise<boolean>;
+
   // --- friends ---
   friendsList(): Promise<AccountRef[]>;
   friendsIncoming(): Promise<AccountRef[]>;