backend phase 7: search & matching (nurse_search_index)

Add the discovery layer: the denormalized nurse_search_index read model
(one row per bookable variant x covered service area), maintained inline
inside each source write's transaction, plus the single public search
query behind the INurseSearch seam.

- Entity + EF config + migration (search schema): covering search index,
  filtered-unique (variant_id, city_id, district_id) pair with NULL
  district participating, nurse_id index, soft-delete.
- ISearchIndexMaintainer (write seam) + SearchIndexMaintainer: reindex
  variant / nurse / fan-out / remove-area / full rebuild, staged in the
  owning source write's unit of work; wired into the b3/b4/b5/b6 handlers.
- INurseSearch (read seam) + SqlNurseSearch (real MVP backend): reads only
  is_searchable=1, category/city/district(NULL-aware)/gender/price filters,
  rating sort, pagination. Elasticsearch deferred (config Search:Backend).
- SearchNursesQuery (+ validator) and RebuildSearchIndexCommand; public
  SearchController (GET search/nurses) + admin AdminSearchController
  (POST admin_search/rebuild_index).
- Tests: 9 DB-backed maintainer/search + 4 WebApplicationFactory; updated
  affected b3/b4/b5/b6 handler tests. Build clean, 167 tests green.
- Docs: server CLAUDE.md project map, contract search.md, swagger refresh,
  handoff, report, mocks-registry rows, STATUS.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/API/Baya.Web.Api/Controllers/V1/AdminSearchController.cs

@@ -0,0 +1,32 @@
+using System.ComponentModel.DataAnnotations;
+using Asp.Versioning;
+using Baya.Application.Features.Search.Commands.RebuildSearchIndex;
+using Baya.Application.Models.Search;
+using Baya.Infrastructure.Identity.Identity.PermissionManager;
+using Baya.WebFramework.Attributes;
+using Baya.WebFramework.BaseController;
+using Baya.WebFramework.ServiceConfiguration;
+using Mediator;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.Mvc;
+using Microsoft.AspNetCore.RateLimiting;
+
+namespace Baya.Web.Api.Controllers.V1;
+
+/// <summary>
+/// Admin maintenance for the search index. The rebuild is the idempotent convergence/reconciliation path —
+/// its result must match the incrementally-maintained index.
+/// </summary>
+[ApiVersion("1")]
+[ApiController]
+[Route("api/v{version:apiVersion}/[controller]")]
+[Authorize(ConstantPolicies.DynamicPermission)]
+[EnableRateLimiting(RateLimitingServiceExtension.SensitivePolicy)]
+[Display(Description = "Admin search-index maintenance (full rebuild / reconciliation)")]
+public sealed class AdminSearchController(ISender sender) : BaseController
+{
+    [HttpPost("[action]")]
+    [ProducesOkApiResponseType<SearchIndexRebuildResult>]
+    public async Task<IActionResult> RebuildIndex(CancellationToken cancellationToken)
+        => OperationResult(await sender.Send(new RebuildSearchIndexCommand(), cancellationToken));
+}

server/src/API/Baya.Web.Api/Controllers/V1/SearchController.cs

@@ -0,0 +1,43 @@
+#nullable enable
+using System.ComponentModel.DataAnnotations;
+using Asp.Versioning;
+using Baya.Application.Features.Search.Queries.SearchNurses;
+using Baya.Application.Models.Common;
+using Baya.Application.Models.Search;
+using Baya.WebFramework.Attributes;
+using Baya.WebFramework.BaseController;
+using Mediator;
+using Microsoft.AspNetCore.Mvc;
+
+namespace Baya.Web.Api.Controllers.V1;
+
+/// <summary>
+/// Public nurse discovery. Pre-auth (families browse before signing in) and covered by the per-IP global
+/// rate limiter. Reads only searchable (verified + accepting + active) rows via the <c>INurseSearch</c> seam.
+/// </summary>
+[ApiVersion("1")]
+[ApiController]
+[Route("api/v{version:apiVersion}/[controller]")]
+[Display(Description = "Public nurse search: category + city/district geo, same-gender filter, price range, rating sort")]
+public sealed class SearchController(ISender sender) : BaseController
+{
+    [HttpGet("[action]")]
+    [ProducesOkApiResponseType<PagedResult<NurseSearchResultDto>>]
+    public async Task<IActionResult> Nurses(
+        [FromQuery(Name = "service_category_id")] long serviceCategoryId,
+        [FromQuery(Name = "city_id")] long cityId,
+        [FromQuery(Name = "district_id")] long? districtId,
+        [FromQuery(Name = "nurse_gender")] string? nurseGender,
+        [FromQuery(Name = "min_price")] long? minPrice,
+        [FromQuery(Name = "max_price")] long? maxPrice,
+        [FromQuery(Name = "price_unit")] string? priceUnit,
+        [FromQuery(Name = "page")] int page,
+        [FromQuery(Name = "page_size")] int pageSize,
+        CancellationToken cancellationToken)
+        => OperationResult(await sender.Send(
+            new SearchNursesQuery(
+                serviceCategoryId, cityId, districtId, nurseGender, minPrice, maxPrice, priceUnit,
+                page <= 0 ? 1 : page,
+                pageSize <= 0 ? Application.Common.Pagination.DefaultPageSize : pageSize),
+            cancellationToken));
+}