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>

svc/llm/tool_wire_policy.py

@@ -13,6 +13,7 @@ from datetime import datetime, timedelta, timezone
 from typing import Any
 
 from svc.llm.tool_schema import MIN_OPENAI_FUNCTION_PARAMETERS, complete_openai_tools_wire_parameters
+from svc.persistence.assistant_store import get_assistant_store
 
 logger = logging.getLogger(__name__)
 
@@ -429,7 +430,7 @@ def prepare_openai_tools_for_llm_api(
             from svc.config.paths import db_path
             from svc.persistence.sqlite_store import SqliteStore
 
-            store = SqliteStore(db_path())
+            store = get_assistant_store()
         # Role-scoped policies if configured; otherwise fall back to global.
         policies = load_tool_policies_dict_for_role(store, role=str(role or "").strip().lower() or None)
         admin = load_merged_admin_config(store)

svc/llm/transports/openai_chat_completions.py

@@ -5,11 +5,18 @@ import logging
 import os
 import re
 import uuid
-from typing import Any, Optional
 from collections.abc import Callable
+from typing import Any, Optional
 
 from svc.llm.tool_schema import complete_openai_tools_wire_parameters
-from svc.llm.transports.base import ChatModel, LLMResponse, LLMToolCall, normalize_image_b64_payload, coerce_thought_signature_for_storage
+from svc.llm.transports.base import (
+    ChatModel,
+    LLMResponse,
+    LLMToolCall,
+    coerce_thought_signature_for_storage,
+    normalize_image_b64_payload,
+)
+from svc.persistence.assistant_store import get_assistant_store
 
 logger = logging.getLogger(__name__)
 
@@ -551,12 +558,10 @@ class OpenAIChatModel(ChatModel):
             kwargs["extra_body"] = extra_body
         if use_tools:
             try:
-                from svc.config.paths import db_path
-                from svc.persistence.sqlite_store import SqliteStore
                 from runtime.tools.exposure_plan import build_llm_tools_plan
 
                 plan = build_llm_tools_plan(
-                    store=SqliteStore(db_path()),
+                    store=get_assistant_store(),
                     role="",
                     base_url=self.base_url,
                     max_json_bytes=_default_max_openai_tools_json_bytes(self.base_url),