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/mock/client.ts

@@ -16,6 +16,8 @@ import type {
   BlockStatus,
   ChatMessage,
   EvalResult,
+  FeedbackReply,
+  FeedbackState,
   FriendCode,
   GameList,
   GcgExport,
@@ -89,6 +91,11 @@ export class MockGateway implements GatewayClient {
   private readonly profile: Profile = { ...PROFILE };
   private readonly subs = new Set<(e: PushEvent) => void>();
   private pendingMatch: string | null = null;
+  // Feedback slice: a submission marks a message pending (blocks resend); mockAdminReply
+  // clears it and raises the badge.
+  private feedbackPending = false;
+  private feedbackReply: FeedbackReply | null = null;
+  private feedbackReplyUnread = false;
   // The most recently opened auto-match game still awaiting an opponent, for the e2e join hook.
   private openGameId: string | null = null;
   private friends: AccountRef[] = MOCK_FRIENDS.map((f) => ({ ...f }));
@@ -409,6 +416,30 @@ export class MockGateway implements GatewayClient {
   async chatList(gameId: string): Promise<ChatMessage[]> {
     return [...this.game(gameId).chat];
   }
+  async feedbackSubmit(_body: string, _attachment: Uint8Array | null, _attachmentName: string, _channel: string): Promise<void> {
+    this.feedbackPending = true;
+  }
+  async feedbackGet(): Promise<FeedbackState> {
+    this.feedbackReplyUnread = false; // fetching the screen delivers (reads) the reply
+    return {
+      canSend: !this.feedbackPending,
+      blockedReason: this.feedbackPending ? 'pending' : '',
+      reply: this.feedbackReply,
+    };
+  }
+  async feedbackUnread(): Promise<boolean> {
+    return this.feedbackReplyUnread;
+  }
+
+  // mockAdminReply simulates an operator reply: it clears the pending message, sets the
+  // reply and raises the badge via a live admin_reply notification. e2e hook:
+  // window.__mock.adminReply.
+  mockAdminReply(body = 'Thanks — we are looking into it.'): void {
+    this.feedbackPending = false;
+    this.feedbackReply = { body, repliedAtUnix: Math.floor(Date.now() / 1000) };
+    this.feedbackReplyUnread = true;
+    this.emit({ kind: 'notify', sub: 'admin_reply' });
+  }
   async nudge(gameId: string): Promise<ChatMessage> {
     const g = this.game(gameId);
     const msg: ChatMessage = {