Initial commit: Telegram Web Client with bot chat sync

- Backend: FastAPI + Telethon v2 WebSocket server
- Frontend: React + TypeScript + Vite + Zustand
- Features: Phone auth, 2FA, real-time bot chat
- Fix: Use chats= instead of from_users= to sync messages from all devices
- Config: BOT_USERNAME=AnvilForgeBot

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/.env.example

@@ -0,0 +1,13 @@
+# Telegram API credentials (get from https://my.telegram.org)
+TELEGRAM_API_ID=12345678
+TELEGRAM_API_HASH=your_api_hash_here
+
+# Bot username to chat with (without @)
+BOT_USERNAME=AnvilForgeBot
+
+# Session storage directory
+SESSION_DIR=/opt/telegram-web-client/sessions
+
+# Server settings
+HOST=0.0.0.0
+PORT=8000