Follow-up polish from the duplicate-subgraph review:
- BaseSqliteStore.clone() now requires an opt-in `_cloneable` flag (default
off), so a new or secret-bearing store can never be cloned by accident —
defence-in-depth on top of the endpoint's `_DUPLICABLE_KINDS` restriction.
Only value-source and colour-strip stores are flagged.
- Fix `_check_name_unique` annotation (`str | None = None`).
- Add tests: `layers[].brightness_source_id` remap, the warnings safety net
firing, the clone allowlist invariant, and clone() refusing a non-cloneable
store.
alexei.dolgolyov
498854f04d