stage-12: Telegram bot adapter

- New src/adapters/telegram_bot.py: full Telegram adapter with python-telegram-bot v22
  - Commands: /start, /help, /clear, /status, /model, /register
  - Inline keyboards for model selection
  - Message routing through existing router.py
  - Private chat: admin-only access
  - Group chat: responds to @mentions and replies to bot
  - Security logging for unauthorized access attempts
  - Message splitting for 4096 char limit
- Updated main.py: runs Discord + Telegram bots concurrently
  - Telegram is optional (gracefully skipped if no telegram_token)
- Updated requirements.txt: added python-telegram-bot>=21.0
- Updated config.json: added telegram_channels section
- Updated cli.py doctor: telegram token check (optional)
- 37 new tests (410 total, zero failures)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main.py

@@ -108,6 +108,16 @@ def main():
             "Heartbeat registered (every %d min)", interval_min
         )
 
+    # Telegram bot (optional — only if telegram_token exists)
+    telegram_token = get_secret("telegram_token")
+    telegram_app = None
+    if telegram_token:
+        from src.adapters.telegram_bot import create_telegram_bot
+        telegram_app = create_telegram_bot(config, telegram_token)
+        logger.info("Telegram bot configured")
+    else:
+        logger.info("No telegram_token — Telegram bot disabled")
+
     # PID file
     PID_FILE.write_text(str(os.getpid()))
 
@@ -122,8 +132,27 @@ def main():
     signal.signal(signal.SIGTERM, handle_signal)
     signal.signal(signal.SIGINT, handle_signal)
 
+    async def _run_all():
+        """Run Discord + Telegram bots concurrently."""
+        tasks = [asyncio.create_task(client.start(token))]
+        if telegram_app:
+            async def _run_telegram():
+                await telegram_app.initialize()
+                await telegram_app.start()
+                await telegram_app.updater.start_polling()
+                logger.info("Telegram bot started polling")
+                try:
+                    while True:
+                        await asyncio.sleep(3600)
+                except asyncio.CancelledError:
+                    await telegram_app.updater.stop()
+                    await telegram_app.stop()
+                    await telegram_app.shutdown()
+            tasks.append(asyncio.create_task(_run_telegram()))
+        await asyncio.gather(*tasks)
+
     try:
-        loop.run_until_complete(client.start(token))
+        loop.run_until_complete(_run_all())
     except KeyboardInterrupt:
         loop.run_until_complete(scheduler.stop())
         loop.run_until_complete(client.close())