Phase 3: Polish & PWA

Backend:
- DB: reactions table, invites table, reply_to column on messages
- gateway/events.go: added REACTION_ADD, REACTION_REMOVE events
- internal/reaction/handlers.go: reaction CRUD with WebSocket broadcast
- internal/invite/handlers.go: invite creation, info, join with code
- gateway/hub.go: presence tracking with idle detection
- gateway/client.go: idle timeout support

Frontend - Social:
- TypingIndicator: real-time 'user is typing...' display
- ReactionBar: emoji reactions on messages with counts
- EmojiPicker: searchable emoji grid for reactions
- ReplyBar: quoted reply display above messages
- MentionPopup: @mention autocomplete with user list

Frontend - PWA:
- manifest.json: PWA manifest with theme color and icons
- sw.js: service worker with cache-first strategy and push support
- stores/push.ts: push notification subscription management
- InstallPrompt: 'Add to Home Screen' banner

Frontend - Mobile:
- MobileNav: bottom nav bar for mobile (servers/channels/chat/members)
- MobileDrawer: slide-out drawer with server bar + channel list
- index.html: PWA meta tags, safe area viewport

Frontend - Polish:
- ThemeToggle: dark/light mode switch with localStorage persistence
- InviteModal: generate invite links with expiry and max uses
- JoinServer: /invite/:code join flow
- stores/typing.ts: typing indicator state management
- stores/presence.ts: real-time presence tracking
- tailwind.config.js: darkMode: 'class', light mode color tokens
- styles/index.css: light mode CSS variable overrides

web/src/stores/push.ts

@@ -0,0 +1,77 @@
+import { create } from 'zustand';
+import { api } from '../lib/api.ts';
+
+interface PushState {
+  isSupported: boolean;
+  isSubscribed: boolean;
+  permission: NotificationPermission;
+  subscribe: () => Promise<void>;
+  unsubscribe: () => Promise<void>;
+  requestPermission: () => Promise<NotificationPermission>;
+}
+
+function urlBase64ToUint8Array(base64String: string): BufferSource {
+  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
+  const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
+  const rawData = window.atob(base64);
+  const outputArray = new Uint8Array(rawData.length);
+  for (let i = 0; i < rawData.length; ++i) {
+    outputArray[i] = rawData.charCodeAt(i);
+  }
+  return outputArray;
+}
+
+export const usePushStore = create<PushState>((set, get) => ({
+  isSupported: 'serviceWorker' in navigator && 'PushManager' in window,
+  isSubscribed: false,
+  permission: 'default',
+
+  requestPermission: async () => {
+    if (!get().isSupported) return 'denied';
+    const permission = await Notification.requestPermission();
+    set({ permission });
+    return permission;
+  },
+
+  subscribe: async () => {
+    if (!get().isSupported) return;
+
+    try {
+      // Register service worker
+      const registration = await navigator.serviceWorker.register('/sw.js');
+      await navigator.serviceWorker.ready;
+
+      // Get VAPID public key from server
+      const { publicKey } = await api.get<{ publicKey: string }>('/push/vapid-key');
+      if (!publicKey) return;
+
+      // Subscribe to push
+      const subscription = await registration.pushManager.subscribe({
+        userVisibleOnly: true,
+        applicationServerKey: urlBase64ToUint8Array(publicKey),
+      });
+
+      // Send subscription to server
+      await api.post('/push/subscribe', subscription.toJSON());
+      set({ isSubscribed: true });
+    } catch (error) {
+      console.error('Failed to subscribe to push:', error);
+    }
+  },
+
+  unsubscribe: async () => {
+    if (!get().isSupported) return;
+
+    try {
+      const registration = await navigator.serviceWorker.ready;
+      const subscription = await registration.pushManager.getSubscription();
+      if (subscription) {
+        await api.post('/push/unsubscribe', { endpoint: subscription.endpoint });
+        await subscription.unsubscribe();
+      }
+      set({ isSubscribed: false });
+    } catch (error) {
+      console.error('Failed to unsubscribe from push:', error);
+    }
+  },
+}));