feat: drop old schema tables (trading_sessions, positions, reasoning_logs)

- Created migration script to drop old tables
- Removed old table creation from database.py
- Added tests to verify old tables are removed and new tables exist
- Migration script can be run standalone with: PYTHONPATH=. python api/migrations/002_drop_old_schema.py

api/migrations/002_drop_old_schema.py

@@ -0,0 +1,42 @@
+"""Drop old schema tables (trading_sessions, positions, reasoning_logs)."""
+
+
+def drop_old_schema(db):
+    """
+    Drop old schema tables that have been replaced by new schema.
+
+    Old schema:
+    - trading_sessions → replaced by trading_days
+    - positions (action-centric) → replaced by trading_days + actions + holdings
+    - reasoning_logs → replaced by trading_days.reasoning_full
+
+    Args:
+        db: Database instance
+    """
+
+    # Drop reasoning_logs (child table first)
+    db.connection.execute("DROP TABLE IF EXISTS reasoning_logs")
+
+    # Drop positions (note: this is the OLD action-centric positions table)
+    # The new schema doesn't have a positions table at all
+    db.connection.execute("DROP TABLE IF EXISTS positions")
+
+    # Drop trading_sessions
+    db.connection.execute("DROP TABLE IF EXISTS trading_sessions")
+
+    db.connection.commit()
+
+    print("✅ Dropped old schema tables: trading_sessions, positions, reasoning_logs")
+
+
+if __name__ == "__main__":
+    """Run migration standalone."""
+    from api.database import Database
+    from tools.deployment_config import get_db_path
+
+    db_path = get_db_path("data/trading.db")
+    db = Database(db_path)
+
+    drop_old_schema(db)
+
+    print(f"✅ Migration complete: {db_path}")