fix: [30388f42] Aktiviere WAL-Modus für Company Explorer Datenbank

- Nutzt SQLAlchemy Events, um PRAGMA journal_mode=WAL beim Verbindungsaufbau zu erzwingen.
- Erhöht den SQLite-Timeout auf 30 Sekunden.
- Behebt die COMMIT / ROLLBACK Endlosschleife und Locking-Fehler im Company Explorer.

company-explorer/backend/database.py

@@ -1,11 +1,22 @@
-from sqlalchemy import create_engine, Column, Integer, String, Text, DateTime, ForeignKey, Float, Boolean, JSON
+from sqlalchemy import create_engine, Column, Integer, String, Text, DateTime, ForeignKey, Float, Boolean, JSON, event
 from sqlalchemy.ext.declarative import declarative_base
 from sqlalchemy.orm import sessionmaker, relationship
 from datetime import datetime
 from .config import settings
 
 # Setup
-engine = create_engine(settings.DATABASE_URL, connect_args={"check_same_thread": False})
+engine = create_engine(
+    settings.DATABASE_URL, 
+    connect_args={"check_same_thread": False, "timeout": 30}
+)
+
+# Enable WAL mode for SQLite
+@event.listens_for(engine, "connect")
+def set_sqlite_pragma(dbapi_connection, connection_record):
+    cursor = dbapi_connection.cursor()
+    cursor.execute("PRAGMA journal_mode=WAL")
+    cursor.close()
+
 SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
 Base = declarative_base()