feat(chat): add SvelteKit web app with full feature parity to mobile

Web app features:
- Auth: Login, Register, Forgot Password with shared-auth-ui
- Chat: New chat, conversation view, message list, model selector
- Templates: List, create, edit, delete templates
- Spaces: Team workspaces with member management
- Documents: Document mode with version history
- Archive & Profile pages

Technical:
- SvelteKit 2 with Svelte 5 runes
- Tailwind CSS 4 with shared themes
- Supabase Auth with SSR
- ChatLogo added to shared-branding
- dev:*:app commands for web+backend

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

chat/backend/package.json

@@ -5,6 +5,7 @@
   "scripts": {
     "build": "nest build",
     "start": "nest start",
+    "dev": "nest start --watch",
     "start:dev": "nest start --watch",
     "start:debug": "nest start --debug --watch",
     "start:prod": "node dist/main",