feat: Add presence heartbeat for Matrix online status

- matrix-gateway: POST /internal/matrix/presence/online endpoint
- usePresenceHeartbeat hook with activity tracking
- Auto away after 5 min inactivity
- Offline on page close/visibility change
- Integrated in MatrixChatRoom component

services/node-registry/app/database.py

@@ -0,0 +1,82 @@
+"""
+SQLite Database connection for local development
+Use this for testing without PostgreSQL
+"""
+import os
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker, Session
+from contextlib import contextmanager
+import logging
+
+logger = logging.getLogger(__name__)
+
+# SQLite database file
+DB_FILE = os.getenv("NODE_REGISTRY_DB_FILE", "node_registry.db")
+DATABASE_URL = f"sqlite:///{DB_FILE}"
+
+# Create engine
+engine = create_engine(
+    DATABASE_URL,
+    connect_args={"check_same_thread": False},  # Required for SQLite
+    echo=os.getenv("NODE_REGISTRY_ENV") == "development",  # Log SQL in dev
+)
+
+# Create session factory
+SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
+
+
+def get_db() -> Session:
+    """
+    Dependency for FastAPI to get database session
+    
+    Usage:
+        @app.get("/")
+        def endpoint(db: Session = Depends(get_db)):
+            ...
+    """
+    db = SessionLocal()
+    try:
+        yield db
+    finally:
+        db.close()
+
+
+@contextmanager
+def get_db_context():
+    """
+    Context manager for database session
+    
+    Usage:
+        with get_db_context() as db:
+            db.query(Node).all()
+    """
+    db = SessionLocal()
+    try:
+        yield db
+        db.commit()
+    except Exception:
+        db.rollback()
+        raise
+    finally:
+        db.close()
+
+
+def check_db_connection() -> bool:
+    """Check if database connection is working"""
+    try:
+        with engine.connect() as conn:
+            conn.execute("SELECT 1")
+        return True
+    except Exception as e:
+        logger.error(f"Database connection failed: {e}")
+        return False
+
+
+def get_db_info() -> dict:
+    """Get database connection information"""
+    return {
+        "type": "sqlite",
+        "database": DB_FILE,
+        "connected": check_db_connection(),
+    }
+