refactor(store): consolidate the SQLite store family into bot_bottle.store

Move the DbStore base (db_store), the shared schema-migration base (migrations /
TableMigrations), the concrete stores (audit_store, config_store, queue_store),
and StoreManager out of the package root into a bot_bottle/store/ package, so
persistence lives in one place rather than scattered across the root.

Callers use direct submodule imports (from bot_bottle.store.store_manager
import StoreManager). Inside the moved modules the relative imports point back
up to their non-store siblings (..paths, ..supervise_types) while co-moved
siblings stay package-local; the flat-import fallbacks are untouched. The
orchestrator's own stores (config_store, secret_store, registry) stay in
orchestrator/ and repoint to the moved DbStore / TableMigrations.

No behavior change; full unit suite green.

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

tests/unit/test_supervise_edge.py

@@ -11,9 +11,9 @@ from pathlib import Path
 from unittest.mock import patch
 
 from bot_bottle import supervise
-from bot_bottle.audit_store import AuditStore
+from bot_bottle.store.audit_store import AuditStore
 from bot_bottle.paths import bot_bottle_root
-from bot_bottle.queue_store import QueueStore
+from bot_bottle.store.queue_store import QueueStore
 from bot_bottle.supervise import (
     AuditEntry,
     Proposal,