refactor(supervise): fold Supervise into the facade as Supervisor; drop dead flat-fallbacks

Move the `Supervise` lifecycle out of its own `orchestrator/supervisor/
supervise.py` and into the package `__init__`, renaming the class to
`Supervisor`. Callers now import it from `bot_bottle.orchestrator.supervisor`
alongside the queue surface it belongs with.

Remove the dead `try/except ImportError` flat-import fallbacks from the
package-only store modules (db_store, audit_store, config_store, queue_store)
and image_cache. Those fallbacks existed for when the store files were
flat-copied into the gateway; post-PRD-0070 the data plane never opens the DB,
so these modules are only ever imported as part of the package. The two gateway
data-plane files that may still be loaded flat (egress_addon_core,
git_gate_render) keep their fallbacks.

Full unit suite green (2251).

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

bot_bottle/image_cache.py

@@ -5,10 +5,7 @@ from __future__ import annotations
 from datetime import datetime, timezone
 from pathlib import Path
 
-try:
-    from .store.config_store import ConfigStore
-except ImportError:
-    from config_store import ConfigStore  # type: ignore[import-not-found]  # pylint: disable=import-error,no-name-in-module
+from .store.config_store import ConfigStore
 
 
 class StaleImageError(Exception):