fix: GET /v1/user_info 500 on missing broker_credentials table (issue #9)

trex-core reported GET /v1/user_info returning 500 for valid service/daemon
tokens (whoami → daemon_id), degrading the daemon and holding new trades. The
reported hypothesis (service-token None deref) was a misdiagnosis. Root cause:

  app/api/v1_user_info.py: credentials = repo.list_broker_credentials(...)
  psycopg.errors.UndefinedTable: relation "broker_credentials" does not exist

The broker_credentials table was missing and the handler only caught
AttributeError, so the DB error propagated to a bare 500.

Two fixes:
1. Handler now degrades gracefully when broker-credential lookup fails — returns
   empty brokers and still serves daemon_id/user_id/permission, which do not
   depend on broker credentials. This is what trex-core's whoami needs.
2. ensure_schema() now also CREATE TABLE broker_credentials (same shape as
   migration 20260502_0014). ensure_schema-bootstrapped DBs were missing it,
   since previously only the alembic path created it.

Added tests/test_v1.py regression: broker-credential lookup raising a DB error
must yield HTTP 200 with daemon_id, not 500. Verified against the real DB
(was 500 → now 200 + daemon_id). Full suite 377 passed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_v1.py

@@ -804,6 +804,37 @@ def test_v1_user_info_returns_user(monkeypatch) -> None:
     assert body["disabled_reason"] is None
 
 
+def test_v1_user_info_degrades_when_broker_credentials_lookup_fails(monkeypatch) -> None:
+    """issue #9 regression: broker_credentials lookup failure (missing table / DB error)
+    must NOT crash /v1/user_info with 500. daemon_id/user_id/permission do not depend on
+    broker credentials — degrade gracefully with empty brokers."""
+    monkeypatch.setenv("PORTFOLIOHUB_DB_ENABLED", "true")
+
+    principal = TokenPrincipal(
+        token_id="t1", user_id="user-1", permission="read",
+        token_type="service", runtime_id="rt-1", daemon_id="daemon-9",
+    )
+    user = User(id="user-1", username="alice", permission="read", is_active=True)
+
+    mock_repo = MagicMock()
+    mock_repo.get_token_principal.return_value = principal
+    mock_repo.get_user.return_value = user
+    mock_repo.list_broker_credentials.side_effect = RuntimeError(
+        'relation "broker_credentials" does not exist'
+    )
+
+    with patch("app.core.auth.get_portfolio_repository_from_settings", return_value=mock_repo), \
+         patch("app.api.v1_user_info.get_portfolio_repository_from_settings", return_value=mock_repo):
+        client = _make_app()
+        resp = client.get("/v1/user_info", headers=_service_token_header())
+
+    assert resp.status_code == 200
+    body = resp.json()
+    assert body["daemon_id"] == "daemon-9"
+    assert body["user_id"] == "user-1"
+    assert body["brokers"] == []
+
+
 def test_v1_user_info_inactive_user_has_disabled_reason(monkeypatch) -> None:
     monkeypatch.setenv("PORTFOLIOHUB_DB_ENABLED", "true")