refactor: extract QueueStore and AuditStore to their own modules

Moves _QueueStore → bot_bottle/queue_store.py (public QueueStore) and
_AuditStore → bot_bottle/audit_store.py (public AuditStore). Removes
the public queue_db_path() function; QueueStore resolves the DB path
via host_db_path() on the host, or via the SUPERVISE_DB_PATH env var
in the sidecar container (internal mechanism, not public API).

Adds queue_store.py and audit_store.py to Dockerfile.sidecars so the
sidecar bundle picks them up. Updates __all__ in supervise.py.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_supervise.py

@@ -20,7 +20,6 @@ from bot_bottle.supervise import (
     archive_proposal,
     host_db_path,
     list_pending_proposals,
-    queue_db_path,
     read_audit_entries,
     read_proposal,
     read_response,
@@ -132,7 +131,7 @@ class TestQueueIO(unittest.TestCase):
         p = _proposal()
         path = write_proposal(p)
         self.assertTrue(path.exists())
-        self.assertEqual(queue_db_path(), path)
+        self.assertEqual(host_db_path(), path)
         self.assertEqual(0o600, path.stat().st_mode & 0o777)
         loaded = read_proposal(self.slug, p.id)
         self.assertEqual(p, loaded)

tests/unit/test_supervise_edge.py

@@ -38,9 +38,6 @@ class TestPathHelpers(unittest.TestCase):
     def test_bot_bottle_root(self) -> None:
         self.assertTrue(str(supervise.bot_bottle_root()).endswith(".bot-bottle"))
 
-    def test_queue_db_path_is_host_db_path(self) -> None:
-        self.assertEqual(supervise.host_db_path(), supervise.queue_db_path())
-
 
 class TestReadMalformed(unittest.TestCase):
     def test_read_proposal_missing_row(self) -> None: