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>

interfaces/ws/auth_and_hello.py

@@ -6,6 +6,7 @@ from typing import Any
 
 from svc.config.paths import db_path
 from svc.persistence.sqlite_store import SqliteStore
+from svc.persistence.assistant_store import get_assistant_store
 
 
 def build_hello_ok_payload(
@@ -50,7 +51,7 @@ def resolve_ws_auth(connect_params: dict[str, Any] | None) -> dict[str, Any]:
         token = device_token or bootstrap_token
     if not token:
         return {}
-    store = SqliteStore(db_path())
+    store = get_assistant_store()
     token_hash = hashlib.sha256(token.encode("utf-8", errors="ignore")).hexdigest()
     session = store.get_auth_session(session_token_hash=token_hash)
     if not session or session.get("revoked_at"):