refactor(orchestrator): move registry into store/registry_store

registry.py is a SQLite-backed store (its class is already RegistryStore),
so it belongs with the other orchestrator-owned stores rather than at the
package root. Moved orchestrator/registry.py -> orchestrator/store/
registry_store.py, joining queue_store / secret_store / config_store.

Repointed the in-package importers (.registry -> .store.registry_store)
and the tests, bumped the moved file's relative-import depths, renamed
the test file to match, and listed it in the store package docstring.
Full unit suite green (2243).

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

bot_bottle/orchestrator/__init__.py

@@ -28,7 +28,7 @@ orchestrator -> firecracker).
 
 from __future__ import annotations
 
-from .registry import BottleRecord, RegistryStore, new_identity_token
+from .store.registry_store import BottleRecord, RegistryStore, new_identity_token
 from .broker import (
     BrokerAuthError,
     LaunchBroker,