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/scripts/install_mcp_sqlite_brave_calendar.py

@@ -15,6 +15,7 @@ sys.path.insert(0, str(ROOT))
 
 from svc.config.paths import db_path  # noqa: E402
 from svc.persistence.sqlite_store import SqliteStore  # noqa: E402
+from svc.persistence.assistant_store import get_assistant_store
 from runtime.tools.mcp.installer import McpServerManifest, install_mcp_server  # noqa: E402
 from runtime.tools.mcp.runtime import McpProcessRuntime  # noqa: E402
 
@@ -61,7 +62,7 @@ def _sync_tools(store: SqliteStore, server_id: str) -> bool:
 
 
 def main() -> None:
-    store = SqliteStore(db_path())
+    store = get_assistant_store()
     db_file = db_path()
 
     bundles: list[McpServerManifest] = [