Add session management utilities for database operations

Introduces `get_session_factory` and `session_scope` context manager for handling database connections and transactions.

Author: brayniverse

src/open_cinema_index/cli.py

@@ -1,11 +1,34 @@
+from contextlib import contextmanager
+
 import typer
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
 
 app = typer.Typer(
     name="oci",
     help="Open Cinema Index — film ingestion and indexing toolkit",
 )
 
 
+def get_session_factory():
+    engine = create_engine("sqlite:///open_cinema_index.db")
+    return sessionmaker(bind=engine)
+
+
+@contextmanager
+def session_scope():
+    session_factory = get_session_factory()
+    session = session_factory()
+    try:
+        yield session
+        session.commit()
+    except Exception:
+        session.rollback()
+        raise
+    finally:
+        session.close()
+
+
 @app.command()
 def fetch(
     source: str = typer.Argument(..., help="Source name (e.g. tmdb, imdb)"),