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>

Dockerfile.sidecars

@@ -66,6 +66,8 @@ COPY bot_bottle/egress_dlp_config.py /app/egress_dlp_config.py
 COPY bot_bottle/egress_addon.py      /app/egress_addon.py
 COPY bot_bottle/dlp_detectors.py     /app/dlp_detectors.py
 COPY bot_bottle/yaml_subset.py       /app/yaml_subset.py
+COPY bot_bottle/queue_store.py       /app/queue_store.py
+COPY bot_bottle/audit_store.py       /app/audit_store.py
 COPY bot_bottle/supervise.py         /app/supervise.py
 COPY bot_bottle/supervise_server.py  /app/supervise_server.py
 COPY bot_bottle/sidecar_init.py      /app/sidecar_init.py