Remove db migration

src/core/database.py

@@ -108,9 +108,3 @@ def get_db():
 def init_db() -> None:
     os.makedirs(DATA_DIR, exist_ok=True)
     Base.metadata.create_all(bind=engine)
-    # Lightweight migrations: add columns that may not exist in older databases
-    with engine.connect() as conn:
-        existing = {row[1] for row in conn.execute(text("PRAGMA table_info(keypasses)"))}
-        if "schedule" not in existing:
-            conn.execute(text("ALTER TABLE keypasses ADD COLUMN schedule TEXT"))
-            conn.commit()