feat(BA-6626): app_config_fragment bulk repository layer

[jopemachine]

Summary

Repository-layer app_config_fragment bulk operations, split out of #12401 (BA-6618) to keep that PR reviewable. No API/service surface here — the service layer stacks on top. Built on the generic partial bulk ops already in WriteOps (bulk_create_partial / bulk_update_partial / bulk_purge_partial) — no new base primitives.

• bulk_create(items: Sequence[GatedAppConfigFragmentCreate]) — each item pairs a fragment CreatorSpec with its allow-list write-gate. The gates are checked in the same transaction as the writes; rejected items are reported per item (batch index + reason) and the allowed items insert each in its own savepoint for partial success.
• bulk_update(updaters) / bulk_purge(purgers) — no write-gate: a fragment row exists only while its allow-list entry does (FK with cascade, feat(BA-6628): cascade fragment deletion from the allow list #12518), so an existing fragment is always writable at its own scope. Missing targets are reconstructed as per-item not-found failures (the generic partial ops silently skip a missing PK).
• The AppConfigFragmentBulkWriteResult data type (succeeded + failed[index, message]).
• Repository tests (real DB): partial create with a rejected gate, partial update/purge with a missing target.

📚 Stacked PRs

Part of the AppConfigFragment / AppConfig stack under BEP-1052 (epic BA-5781). Merge in order:

1. ✅ feat(BA-6552): add app_config_fragments DB model and Alembic migration #12306 — feat(BA-6552): app_config_fragments DB model and Alembic migration
2. ✅ feat(BA-6553): add app_config_fragments repository layer #12307 — feat(BA-6553): repository layer
3. ✅ refactor(BA-6619): consolidate AppConfigScopeType into common.data (single definition) #12403 — refactor(BA-6619): consolidate AppConfigScopeType into common.data
4. ✅ refactor(BA-6620): ExistsQuerier ops primitive + AppConfigAllowList.exists #12405 — refactor(BA-6620): ExistsQuerier + AppConfigAllowList.exists
5. ✅ feat(BA-6554): add app_config_fragment service layer #12358 — feat(BA-6554): AppConfigFragment service layer
6. feat(BA-6628): move fragment rank to the allow list with scope defaults #12516 — feat(BA-6628): move fragment rank to the allow list with scope defaults (replaces feat(BA-6628): conditional-bulk repository primitives #12429)
7. feat(BA-6628): expose allow-list rank on the v2 API surface #12517 — feat(BA-6628): expose allow-list rank on the v2 API surface
8. feat(BA-6628): cascade fragment deletion from the allow list #12518 — feat(BA-6628): cascade fragment deletion from the allow list
9. 👉 feat(BA-6626): app_config_fragment bulk repository layer #12426 — feat(BA-6626): app_config_fragment bulk repository layer ← you are here
10. feat(BA-6618): app_config_fragment bulk CRUD service layer #12401 — feat(BA-6618): AppConfigFragment bulk CRUD service layer
11. feat(BA-6555): add app_config service layer #12359 — feat(BA-6555): app_config service layer (merge engine)
12. feat(BA-6556): AppConfig REST v2 API (raw fragments and merged read/update) #12377 — feat(BA-6556): AppConfig REST v2 API

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📚 Documentation preview 📚: https://sorna--12426.org.readthedocs.build/en/12426/

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📚 Documentation preview 📚: https://sorna-ko--12426.org.readthedocs.build/ko/12426/

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📚 Documentation preview 📚: https://sorna--12426.org.readthedocs.build/en/12426/

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📚 Documentation preview 📚: https://sorna-ko--12426.org.readthedocs.build/ko/12426/