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/server_methods_bridge.py

@@ -6,6 +6,7 @@ from typing import Any, Callable
 
 from svc.config.paths import db_path
 from svc.persistence.sqlite_store import SqliteStore
+from svc.persistence.assistant_store import get_assistant_store
 from interfaces.gateway.context_builder import build_common_gateway_context
 
 
@@ -22,7 +23,7 @@ def build_gateway_context(
     validate_relay_share_envelope: Callable[[dict[str, Any]], tuple[bool, str, dict[str, Any]]],
     now_ms: Callable[[], int],
 ) -> dict[str, Any]:
-    store = SqliteStore(db_path())
+    store = get_assistant_store()
 
     def _abort_chat_run(run_id: str) -> bool:
         rid = str(run_id or "").strip()