feat(BA-6922): AppConfig fragment search REST v2 API (admin + scoped)

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📚 Stacked PRs

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

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-6702): move fragment rank to the allow list with scope defaults #12516 — feat(BA-6702): move fragment rank to the allow list with scope defaults
7. ✅ feat(BA-6701): expose allow-list rank on the v2 API surface #12517 — feat(BA-6701): expose allow-list rank on the v2 API surface
8. ✅ feat(BA-6704): cascade app config subtree deletion from the definition #12518 — feat(BA-6704): cascade app config subtree deletion from the definition
9. ✅ feat(BA-6626): app_config_fragment bulk repository layer #12426 — feat(BA-6626): app_config_fragment bulk repository layer
10. ✅ feat(BA-6618): app_config_fragment bulk CRUD service layer #12401 — feat(BA-6618): app_config_fragment bulk CRUD service layer
11. ✅ feat(BA-6810): AppConfigFragment visible-fragments query (repository layer) #12706 — feat(BA-6810): AppConfigFragment visible-fragments query (repository layer)
12. ✅ feat(BA-6859): bind AppConfig fragments to their RBAC scope on write (repository layer) #12826 — feat(BA-6859): bind fragments to their RBAC scope on write (repository layer)
13. ✅ feat(BA-6872): seed APP_CONFIG_FRAGMENT permissions into the RBAC role fixture #12837 — fix(BA-6872): seed APP_CONFIG_FRAGMENT permissions into the RBAC role fixture
14. ✅ chore(BA-6873): drop the dead APP_CONFIG RBAC entity type #12839 — chore(BA-6873): drop the dead APP_CONFIG RBAC entity type
15. ✅ feat(BA-6555): AppConfig merge engine + resolve service (service layer) #12359 — feat(BA-6555): AppConfig merge engine + resolve service (service layer)
16. ✅ refactor(BA-6948): store app_config_fragments.scope_id as a nullable UUID #12984 — feat(BA-6948): store app_config_fragments.scope_id as a nullable UUID
17. feat(BA-6921): AppConfig fragment write REST v2 API (CRUD) #12928 — feat(BA-6921): AppConfig fragment write REST v2 API (CRUD)
18. 👉 feat(BA-6922): AppConfig fragment search REST v2 API (admin + scoped) #12930 — feat(BA-6922): AppConfig fragment search REST v2 API (admin + scoped) ← you are here
19. feat(BA-6556): merged AppConfig REST v2 read API #12377 — feat(BA-6556): merged AppConfig REST v2 read API

Fork at #12928: the fragment search (#12930) and the merged-read (#12377) both stack on #12928 and can merge in either order once it lands.

Summary

Fragment search REST v2 surface, split out of the write PR (BA-6921, #12928) to keep each PR review-sized. Two variants:

• POST /v2/app-config-fragments/search — system-wide paginated search (superadmin).
• POST /v2/app-config-fragments/scoped-search — principal-visible search (auth), the REST surface of the visible-fragments query (BA-6810, feat(BA-6810): AppConfigFragment visible-fragments query (repository layer) #12706).

What's included

• DTOs: AppConfigFragmentFilter, AppConfigFragmentOrder, SearchAppConfigFragmentInput, AppConfigFragmentScope, ScopedSearchAppConfigFragmentInput, plus types.py (order field + scope-type filter) and SearchAppConfigFragmentPayload.
• Adapter: admin_search / scoped_search + the filter / order / scope-type query converters.
• REST: the two search routes on the existing app-config-fragments sub-app.

Reuses AppConfigFragmentNode from #12928. No processor change — the admin_search / scoped_search service processors already exist; this PR only adds the API surface.

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📚 Documentation preview 📚: https://sorna--12930.org.readthedocs.build/en/12930/

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📚 Documentation preview 📚: https://sorna-ko--12930.org.readthedocs.build/ko/12930/

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📚 Documentation preview 📚: https://sorna--12930.org.readthedocs.build/en/12930/

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📚 Documentation preview 📚: https://sorna-ko--12930.org.readthedocs.build/ko/12930/

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📚 Documentation preview 📚: https://sorna--12930.org.readthedocs.build/en/12930/

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📚 Documentation preview 📚: https://sorna-ko--12930.org.readthedocs.build/ko/12930/

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📚 Documentation preview 📚: https://sorna--12930.org.readthedocs.build/en/12930/

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📚 Documentation preview 📚: https://sorna-ko--12930.org.readthedocs.build/ko/12930/

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This type doesn't represent public scope

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This PR was auto-closed by GitHub after a rebase mistake briefly made the head branch equal its base (head == base, zero diff). GitHub refuses to reopen a PR in that state. No code was lost. Recreated as #13020 with the same branch and commit — please continue review there.