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/tools/public/index_workspace_tool.py

@@ -3,17 +3,16 @@ from __future__ import annotations
 from typing import Any
 
 from runtime.tools.base import ToolSpec
+from svc.persistence.assistant_store import get_assistant_store
 
 
 def index_workspace_tool() -> ToolSpec:
     def handler(args: dict[str, Any]) -> dict[str, Any]:
         max_files = int(args.get("max_files") or 120)
         try:
-            from svc.persistence.sqlite_store import SqliteStore
-            from svc.config.paths import db_path
             from runtime.tools.workspace_indexer import index_workspace
 
-            store = SqliteStore(db_path())
+            store = get_assistant_store()
             st = index_workspace(store, max_files=max(1, min(max_files, 800)))
             return {"ok": True, "files_seen": st.files_seen, "chunks_upserted": st.chunks_upserted, "embeddings_upserted": st.embeddings_upserted}
         except Exception as e: