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/tailwind.config.js

@@ -4,6 +4,7 @@ export default {
     "./index.html",
     "./src/**/*.{js,ts,jsx,tsx}",
   ],
+  darkMode: 'class',
   theme: {
     extend: {
       colors: {
@@ -24,6 +25,16 @@ export default {
         'gb-aqua': '#8ec07c',
         'gb-orange': '#fe8019',
         'gb-gray': '#928374',
+        // Light mode overrides
+        'gb-light-bg-h': '#f9f5d7',
+        'gb-light-bg': '#fbf1c7',
+        'gb-light-bg-s': '#ebdbb2',
+        'gb-light-bg-t': '#d5c4a1',
+        'gb-light-bg-f': '#bdae93',
+        'gb-light-fg': '#282828',
+        'gb-light-fg-s': '#3c3836',
+        'gb-light-fg-t': '#504945',
+        'gb-light-fg-f': '#7c6f64',
       },
       fontFamily: {
         mono: ['"JetBrains Mono"', '"Fira Code"', '"Cascadia Code"', '"SF Mono"', 'Consolas', '"Liberation Mono"', 'monospace'],