Align remaining controllers to domain responses

[WilliamAGH]

Objective\nReplace remaining Map/ad-hoc response shapes in web controllers with domain response records, keeping domain framework-free and contracts explicit.\n\n## Inventory (current Map/ad-hoc usage)\n- BaseController: handleServiceException/handleValidationException/createSuccessResponse use Map\n- ExceptionResponseBuilder: buildErrorResponse/buildSuccessResponse return Map\n- IngestionController: /api/ingest and /api/ingest/local return Map\n- CustomErrorController: handleApiError returns Map\n\n## Tasks\n- [ ] Create domain package for ingestion responses (e.g., )\n - [ ] Add (fields: , )\n - [ ] Add (fields: , , )\n - [ ] Add (fields: , , nullable)\n - [ ] Add sealed interfaces and with permitted types\n - [ ] Javadoc all public records per JD1–JD8\n- [ ] Create domain error response(s) for API errors (e.g., )\n - [ ] Add (fields: , , nullable)\n - [ ] Add sealed interface if reused beyond CustomErrorController/BaseController\n - [ ] Ensure no Spring/HTTP imports in domain\n- [ ] Refactor ExceptionResponseBuilder to return domain responses\n - [ ] Replace Map returns with domain response records\n - [ ] Remove HashMap/Map usage\n- [ ] Refactor BaseController to use domain responses\n - [ ] Update method signatures to ResponseEntity of domain response interface\n- [ ] Refactor IngestionController to return domain responses\n - [ ] /api/ingest -> on success\n - [ ] /api/ingest/local -> on success\n - [ ] Validation + IO/runtime errors -> \n - [ ] Update method Javadocs to remove Map references\n- [ ] Refactor CustomErrorController API path to return domain error response\n - [ ] Replace Map response with \n- [ ] Update any tests asserting old Map shapes\n - [ ] WebMvc/MockMvc tests (if present) should assert new JSON fields\n- [ ] Verify policy compliance\n - [ ] No Map<String,Object> in controllers for these paths\n - [ ] Domain types free of framework imports\n - [ ] No generic identifiers (ND rules)\n\n## Validation\n- [ ] Run > Task :compileJava UP-TO-DATE

Task :processResources UP-TO-DATE
Task :classes UP-TO-DATE
Task :compileTestJava UP-TO-DATE
Task :processTestResources UP-TO-DATE
Task :testClasses UP-TO-DATE
18:23:26.034 [Thread-20] �[34mINFO �[0;39m �[36mEMBEDDING_CACHE�[0;39m - Saving cache before shutdown...
18:23:26.034 [Thread-20] �[34mINFO �[0;39m �[36mEMBEDDING_CACHE�[0;39m - Exporting 0 cached embeddings
18:23:26.036 [Thread-20] �[34mINFO �[0;39m �[36mEMBEDDING_CACHE�[0;39m - Successfully exported cache
18:23:26.036 [Thread-20] �[34mINFO �[0;39m �[36mEMBEDDING_CACHE�[0;39m - Cache saved successfully. Total embeddings cached: 0
Task :test

BUILD SUCCESSFUL in 5s
5 actionable tasks: 1 executed, 4 up-to-date
Consider enabling configuration cache to speed up this build: https://docs.gradle.org/9.2.1/userguide/configuration_cache_enabling.html\n- [ ] If failures, update tests or domain contracts accordingly\n