test(persistence): PR8 T8.6 — verify all 3 PR8 tables auto-created

Adds tests/test_pr8_metadata_registration.py: opens a fresh SQLite
engine via init_engine() and asserts inspect(conn).get_table_names()
contains service_accounts, api_keys, and external_users. Guards
against an ORM row class being added under deerflow/persistence/* but
accidentally left out of deerflow/persistence/models/__init__.py —
which would leave the table un-provisioned at startup and surface as
a confusing "no such table" later in Stage 1.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

backend/tests/test_pr8_metadata_registration.py

@@ -0,0 +1,42 @@
+"""Acceptance test for PR8: ``Base.metadata.create_all()`` automatically
+provisions ``service_accounts`` / ``api_keys`` / ``external_users``.
+
+The harness layer registers all ORM models through ``deerflow.persistence.models``
+(imported for side effects from ``engine.init_engine``). This test guards
+against a row class being defined but accidentally left out of the
+registration entry point — a class table that never gets created at
+``init_engine`` time would otherwise silently break Stage 1 once the
+API-key auth layer starts inserting rows.
+"""
+
+from __future__ import annotations
+
+import pytest
+from sqlalchemy import inspect
+
+pytestmark = pytest.mark.anyio
+
+
+@pytest.fixture
+def anyio_backend() -> str:
+    return "asyncio"
+
+
+async def test_pr8_tables_present_after_init_engine(tmp_path):
+    from deerflow.persistence.engine import close_engine, get_engine, init_engine
+
+    url = f"sqlite+aiosqlite:///{tmp_path / 'test.db'}"
+    await init_engine("sqlite", url=url, sqlite_dir=str(tmp_path))
+    try:
+        engine = get_engine()
+        assert engine is not None
+
+        def _table_names(sync_conn):
+            return set(inspect(sync_conn).get_table_names())
+
+        async with engine.connect() as conn:
+            tables = await conn.run_sync(_table_names)
+
+        assert {"service_accounts", "api_keys", "external_users"}.issubset(tables), f"PR8 tables missing from create_all: have {sorted(tables)}"
+    finally:
+        await close_engine()