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>

tests/test_sa_chat_sessions.py

@@ -0,0 +1,52 @@
+"""SQLAlchemy slice tests: chat_session list + CRUD (phase-3 migration)."""
+
+from __future__ import annotations
+
+import pytest
+
+from svc.persistence.db.engine import clear_assistant_engine_cache
+from svc.persistence.sqlite_store import SqliteStore
+
+
+@pytest.fixture
+def fresh_sqlite_store(monkeypatch: pytest.MonkeyPatch, tmp_path):
+    monkeypatch.delenv("AIA_ASSISTANT_DB_BACKEND", raising=False)
+    monkeypatch.setenv("OPS_WORKSPACE_ROOT", str(tmp_path))
+    dbfile = tmp_path / "sa_chat.sqlite"
+    monkeypatch.setenv("AIA_ASSISTANT_DB_PATH", str(dbfile))
+    clear_assistant_engine_cache()
+    s = SqliteStore(str(dbfile))
+    try:
+        yield s
+    finally:
+        clear_assistant_engine_cache()
+
+
+def test_sa_chat_session_crud(fresh_sqlite_store: SqliteStore) -> None:
+    s = fresh_sqlite_store
+    meta0 = s.get_sessions_list_meta()
+    assert meta0.session_count == 0
+    sess = s.create_session("Hi")
+    assert s.get_session(sess.id) is not None
+    assert s.get_session(sess.id).title == "Hi"
+    assert s.count_sessions() == 1
+    s.rename_session(sess.id, "Hi2")
+    assert s.get_session(sess.id).title == "Hi2"
+    listed = s.list_sessions(limit=5, offset=0)
+    assert len(listed) == 1
+    s.delete_session(sess.id)
+    assert s.get_session(sess.id) is None
+
+
+def test_sa_chat_session_user_scoped(fresh_sqlite_store: SqliteStore) -> None:
+    s = fresh_sqlite_store
+    t = s.create_tenant("ChatT")
+    u = s.create_user(tenant_id=t["id"], display_name="ChatU", role="member")
+    sess = s.create_session_for_user(title="Owned", tenant_id=t["id"], user_id=u["id"])
+    rows = s.list_sessions_for_user(tenant_id=t["id"], user_id=u["id"], limit=10, offset=0)
+    assert len(rows) == 1
+    assert rows[0].id == sess.id
+    assert s.get_session_for_user(session_id=sess.id, tenant_id=t["id"], user_id=u["id"]) is not None
+    assert s.get_session_in_tenant(session_id=sess.id, tenant_id=t["id"]) is not None
+    assert s.delete_session_for_user(session_id=sess.id, tenant_id=t["id"], user_id=u["id"]) is True
+    assert s.get_session(sess.id) is None