Initial MCM project: FastAPI + Textual TUI unified messenger

MultiCustomerMessenger supporting Telegram (python-telegram-bot),
WhatsApp (Green API) and SMS (python-gsmmodem-new). REST API with
Bearer-token auth, SQLAlchemy models for MariaDB, APScheduler for
background polling, and Textual TUI running in same asyncio event-loop.

api/routes/channels.py

@@ -0,0 +1,48 @@
+from datetime import datetime
+
+from fastapi import APIRouter, Depends
+
+from api.auth import require_api_key
+from config import settings
+from schemas import ChannelStatusResponse, ChannelType, SystemStatusResponse
+
+router = APIRouter(prefix="/channels", tags=["channels"])
+
+# Wird in main.py gesetzt
+_channel_registry: dict = {}
+
+
+def register(telegram: object, whatsapp: object, sms: object) -> None:
+    _channel_registry["telegram"] = telegram
+    _channel_registry["whatsapp"] = whatsapp
+    _channel_registry["sms"] = sms
+
+
+@router.get("/status", response_model=SystemStatusResponse)
+async def channel_status(_: str = Depends(require_api_key)):
+    statuses = []
+
+    for name, channel_type in [
+        ("telegram", ChannelType.telegram),
+        ("whatsapp", ChannelType.whatsapp),
+        ("sms", ChannelType.sms),
+    ]:
+        ch = _channel_registry.get(name)
+        if ch is None:
+            statuses.append(
+                ChannelStatusResponse(channel=channel_type, enabled=False, connected=False)
+            )
+            continue
+        connected, detail = await ch.check_connection()
+        enabled = (
+            settings.telegram_enabled
+            if name == "telegram"
+            else (settings.whatsapp_enabled if name == "whatsapp" else settings.sms_enabled)
+        )
+        statuses.append(
+            ChannelStatusResponse(
+                channel=channel_type, enabled=enabled, connected=connected, detail=detail
+            )
+        )
+
+    return SystemStatusResponse(channels=statuses, database=True, timestamp=datetime.utcnow())