Review fix: owner-account fallback seed for first setup

Review round 4 (Codex gpt-5.6-terra, HIGH): relying on the flow
context alone can leave first setup ownerless. seed_setup_admin gains
an owner_ids tier: when no persisted copy and no context user exist,
every HA owner account is seeded (owners can already do everything in
HA — no privilege escalation). __init__ resolves owners via
hass.auth.async_get_users on both setup paths; conftest's hass gains
the auth surface. Tests: owner fallback seeds only owners, context
user still wins over owners, owner_ids argument validation. Suite:
910 passed.

tests/conftest.py

@@ -29,7 +29,7 @@ import tempfile
 import weakref
 from pathlib import Path
 from types import SimpleNamespace
-from unittest.mock import MagicMock
+from unittest.mock import AsyncMock, MagicMock
 
 import pytest
 
@@ -281,6 +281,10 @@ def make_hass() -> tuple:
         config=MagicMock(),
         config_entries=SimpleNamespace(async_reload=None),
     )
+    # hass.auth mirrors the real surface the integration reads: an
+    # async_get_users list the tests can repoint at will (the setup
+    # path resolves HA owner accounts as the last-resort admin seed).
+    hass.auth = SimpleNamespace(async_get_users=AsyncMock(return_value=[]))
 
     def _cleanup_config_dir():
         import shutil