feat: chat — ⋮ room menu, typing indicator, online presence, read receipts

- RoomRow: ⋮ button (hover) for pin/unpin context menu
- MessageBubble: right-click context menu with emoji reactions + edit/delete
- Typing indicator: debounced setTyping, animated TypingDots, polling getTyping every 2s
- Online presence: heartbeat setPresence every 30s, green dot on avatars/header
- Read receipts: ✓/✓✓ for own messages in direct rooms via otherUserLastRead
- Migration 075: chat_presence + chat_typing tables
- Context menus clamped to viewport bounds

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/api.ts

@@ -364,6 +364,14 @@ export const api = {
       req<ChatSearchResult[]>('GET', `/api/hotels/${slug}/chat/search?q=${encodeURIComponent(q)}`),
     notify: (slug: string, text: string, systemName?: string) =>
       req<ChatMessage>('POST', `/api/hotels/${slug}/chat/notify`, { text, system_name: systemName }),
+    setPresence: (slug: string) =>
+      req<{ ok: boolean }>('POST', `/api/hotels/${slug}/chat/presence`, {}),
+    getPresence: (slug: string) =>
+      req<string[]>('GET', `/api/hotels/${slug}/chat/presence`),
+    setTyping: (slug: string, roomId: string, typing: boolean) =>
+      req<{ ok: boolean }>('POST', `/api/hotels/${slug}/chat/rooms/${roomId}/typing`, { typing }),
+    getTyping: (slug: string, roomId: string) =>
+      req<string[]>('GET', `/api/hotels/${slug}/chat/rooms/${roomId}/typing`),
   },
 
   // ── Workstations ──────────────────────────────────────────────────────────
@@ -1333,6 +1341,7 @@ export interface ChatRoom {
   lastSender: string | null
   otherUserName: string | null
   otherUserId: string | null
+  otherUserLastRead: string | null
 }
 
 export interface ChatReaction {