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/backend/resolve_common.py

@@ -29,7 +29,7 @@ from ..git_gate import GitGate, GitGatePlan
 from ..log import die
 from ..manifest import Manifest, ManifestBottle
 from ..supervisor.plan import SupervisePlan
-from ..orchestrator.supervisor.supervise import Supervise
+from ..orchestrator.supervisor import Supervisor
 from . import BottleSpec
 
 
@@ -102,7 +102,7 @@ def prepare_supervise(bottle: ManifestBottle, slug: str) -> SupervisePlan | None
         return None
     supervise_dir = supervise_state_dir(slug)
     supervise_dir.mkdir(parents=True, exist_ok=True)
-    return Supervise().prepare(slug, supervise_dir)
+    return Supervisor().prepare(slug, supervise_dir)
 
 
 def merge_provision_env_vars(provision: AgentProvisionPlan) -> AgentProvisionPlan: