feat(persistence): PostgreSQL assistant store, chat persist fixes, gateway scripts

- Add SQLAlchemy Core repos, pg adapter/compat, assistant_store factory, Alembic bootstrap and migration/cutover scripts.

- Harden chat_message writes (NUL scrub for PG), turn_uuid on attempt failure, WS turn_runner fallbacks and gateway executed_turn_uuid init.

- start_gateway: log paths, PS7 stderr handling via cmd, background stdout/stderr redirect; runtime assistant_runtime_log_dir export.

- Ops: clear_all_chat_sessions with PG-only --postgresql and env-gated wipe; clear_postgres_chat_sessions.ps1.

- Tests: SA repos, pg compat, persist fallback, smoke env isolation; CI and docs touch-ups.

Co-authored-by: Cursor <cursoragent@cursor.com>

runtime/operations/providers/wecom.py

@@ -9,6 +9,7 @@ from argparse import _SubParsersAction
 from interfaces.channels.wecom.longconn_runner import run_forever as run_wecom_longconn
 from svc.config.paths import db_path
 from svc.persistence.sqlite_store import SqliteStore
+from svc.persistence.assistant_store import get_assistant_store
 
 from .base import ChannelProvider
 
@@ -32,7 +33,7 @@ _CLEAR_KEYS = [
 
 
 def _store() -> SqliteStore:
-    return SqliteStore(db_path())
+    return get_assistant_store()
 
 
 class WecomProvider(ChannelProvider):