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/conversations.py

@@ -0,0 +1,66 @@
+from fastapi import APIRouter, Depends, HTTPException, Query
+from sqlalchemy.orm import Session
+
+from api.auth import require_api_key
+from db.database import get_db
+from schemas import ConversationResponse, MessageResponse
+from services import conversation_service
+
+router = APIRouter(prefix="/conversations", tags=["conversations"])
+
+
+@router.get("/", response_model=list[ConversationResponse])
+def list_conversations(
+    channel: str | None = Query(None),
+    archived: bool = Query(False),
+    db: Session = Depends(get_db),
+    _: str = Depends(require_api_key),
+):
+    convs = conversation_service.get_all(db, channel=channel, archived=archived)
+    result = []
+    for conv in convs:
+        last_msg = conv.messages[-1] if conv.messages else None
+        result.append(
+            ConversationResponse(
+                **{
+                    c.key: getattr(conv, c.key)
+                    for c in conv.__table__.columns
+                },
+                last_message=MessageResponse.model_validate(last_msg) if last_msg else None,
+                unread_count=conversation_service.unread_count(db, conv.id),
+            )
+        )
+    return result
+
+
+@router.get("/{conv_id}", response_model=ConversationResponse)
+def get_conversation(
+    conv_id: str,
+    db: Session = Depends(get_db),
+    _: str = Depends(require_api_key),
+):
+    conv = conversation_service.get_by_id(db, conv_id)
+    if not conv:
+        raise HTTPException(status_code=404, detail="Conversation not found")
+    last_msg = conv.messages[-1] if conv.messages else None
+    return ConversationResponse(
+        **{c.key: getattr(conv, c.key) for c in conv.__table__.columns},
+        last_message=MessageResponse.model_validate(last_msg) if last_msg else None,
+        unread_count=conversation_service.unread_count(db, conv.id),
+    )
+
+
+@router.get("/{conv_id}/messages", response_model=list[MessageResponse])
+def get_messages(
+    conv_id: str,
+    limit: int = Query(50, ge=1, le=200),
+    offset: int = Query(0, ge=0),
+    db: Session = Depends(get_db),
+    _: str = Depends(require_api_key),
+):
+    conv = conversation_service.get_by_id(db, conv_id)
+    if not conv:
+        raise HTTPException(status_code=404, detail="Conversation not found")
+    msgs = conversation_service.get_messages(db, conv_id, limit=limit, offset=offset)
+    conversation_service.mark_all_read(db, conv_id)
+    return [MessageResponse.model_validate(m) for m in msgs]