test: cover QueueStore/AuditStore guard branches and supervise bundle spec

Add 8 tests covering the branches that were keeping diff-coverage below
90%: explicit db_path constructor arg, early-return guards when the DB
file is absent, _chmod OSError swallowing in both store classes, and the
supervise volume/env/daemon path in _bundle_launch_spec.

Diff-coverage rises from 89.2% to 94.6% (176/186 changed lines).

tests/unit/test_smolmachines_provision.py

@@ -422,6 +422,14 @@ class TestBundleLaunchSpec(unittest.TestCase):
             spec.environment,
         )
 
+    def test_supervise_adds_daemon_volume_and_env(self):
+        from bot_bottle.supervise import DB_PATH_IN_CONTAINER
+        plan = _plan(supervise=True)
+        spec = _bundle_launch_spec(plan, "net", "127.0.0.16")
+        self.assertIn("supervise", spec.daemons_csv)
+        self.assertIn(f"SUPERVISE_DB_PATH={DB_PATH_IN_CONTAINER}", spec.environment)
+        self.assertIn(("/tmp/bot-bottle.db", DB_PATH_IN_CONTAINER, False), spec.volumes)
+
     def test_canary_env_visible_to_smolvm_guest(self):
         plan = _plan(canary=True)
         with patch.object(