fix: sync_plugin_schema sys.path + mail migration columns

- sync_plugin_schema.py: add /app to sys.path for container execution
- mail 0001_initial.sql: add sent/drafts/spam/trash folder columns

scripts/sync_plugin_schema.py

@@ -21,6 +21,10 @@ import sys
 import logging
 from typing import Any
 
+# Ensure /app is in sys.path for container execution
+if "/app" not in sys.path:
+    sys.path.insert(0, "/app")
+
 from sqlalchemy import inspect, text
 from sqlalchemy.dialects.postgresql import dialect as pg_dialect
 from sqlalchemy.ext.asyncio import create_async_engine