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

internal/db/db.go

@@ -88,6 +88,7 @@ CREATE TABLE IF NOT EXISTS messages (
 	channel_id UUID NOT NULL REFERENCES channels(id) ON DELETE CASCADE,
 	author_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
 	content TEXT NOT NULL,
+	reply_to UUID REFERENCES messages(id) ON DELETE SET NULL,
 	edited_at TIMESTAMPTZ,
 	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
 );
@@ -112,4 +113,28 @@ CREATE TABLE IF NOT EXISTS member_roles (
 CREATE INDEX IF NOT EXISTS idx_messages_channel_created ON messages(channel_id, created_at DESC);
 CREATE INDEX IF NOT EXISTS idx_sessions_token ON sessions(token);
 CREATE INDEX IF NOT EXISTS idx_members_server_user ON members(server_id, user_id);
+
+CREATE TABLE IF NOT EXISTS reactions (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	message_id UUID NOT NULL REFERENCES messages(id) ON DELETE CASCADE,
+	user_id UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	emoji VARCHAR(64) NOT NULL,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW(),
+	UNIQUE (message_id, user_id, emoji)
+);
+
+CREATE INDEX IF NOT EXISTS idx_reactions_message ON reactions(message_id);
+
+CREATE TABLE IF NOT EXISTS invites (
+	id UUID PRIMARY KEY DEFAULT gen_random_uuid(),
+	code VARCHAR(16) NOT NULL UNIQUE,
+	server_id UUID NOT NULL REFERENCES servers(id) ON DELETE CASCADE,
+	created_by UUID NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+	expires_at TIMESTAMPTZ,
+	max_uses INTEGER,
+	use_count INTEGER NOT NULL DEFAULT 0,
+	created_at TIMESTAMPTZ NOT NULL DEFAULT NOW()
+);
+
+CREATE INDEX IF NOT EXISTS idx_invites_code ON invites(code);
 `