fix: client perms, @everyone/@channel, docs, unit tests

- usePermissions ORs current user roles + @everyone only (not all server roles)
- cache myRolesByServer; load on active server; refresh after self role edit
- gate/notify @everyone and @channel; plain @username push; special mention UI
- refresh FEATURE_PARITY (DMs exist; drop stale critical gaps)
- README production deploy notes dumpster.service
- unit tests for permission bits and broadcast mention tokens

web/src/components/Layout.tsx

@@ -6,6 +6,7 @@ import { useWebSocketStore } from '../stores/ws.ts';
 import { useServerStore } from '../stores/server.ts';
 import { useChannelStore } from '../stores/channel.ts';
 import { useLayoutStore } from '../stores/layout.ts';
+import { useRoleStore } from '../stores/role.ts';
 import { ServerBar } from './ServerBar.tsx';
 import { ChannelList } from './ChannelList.tsx';
 import { ConversationList } from './ConversationList.tsx';
@@ -43,9 +44,18 @@ export function Layout() {
   const setMobileView = useLayoutStore((s) => s.setMobileView);
   const [showServerSettings, setShowServerSettings] = useState(false);
   const activeServerId = useServerStore((s) => s.activeServerId);
+  const fetchRoles = useRoleStore((s) => s.fetchRoles);
+  const fetchMyRoles = useRoleStore((s) => s.fetchMyRoles);
   const currentVoiceRoom = useVoiceStore((s) => s.currentRoom);
   const [activeTab, setActiveTab] = useState<'chat' | 'voice'>('chat');
 
+  // Load server roles + current user's role assignments for accurate client permission gates.
+  useEffect(() => {
+    if (!activeServerId || !user?.id) return;
+    void fetchRoles(activeServerId);
+    void fetchMyRoles(activeServerId, user.id);
+  }, [activeServerId, user?.id, fetchRoles, fetchMyRoles]);
+
   useEffect(() => {
     if (currentVoiceRoom) setActiveTab('voice');
     else setActiveTab('chat');