DATA-2: new schema entities + Minimal API endpoints + Scalar + DAL teardown

- Entities: Breeder->Contact, +Enclosure/ColorVariety/GerbilPhoto/HealthRecord/WeightRecord;
  Gerbil expanded (single Genotype text col, Status/Gender enums-as-string, FK ids,
  ImportSource/ExternalRef provenance); Litter Strength->TotalBorn +ExpectedGoHomeDate/Notes.
  ColorVariety HasData seed = 18 from GEN-1 catalog. Gerbil<->Litter cycle handled
  (SetNull/Restrict). Enums stored as strings.
- Minimal API (no controllers): Endpoints/*.cs MapGroup+TypedResults for gerbils, litters,
  contacts, enclosures, color-varieties, health/weight-records, inbreeding (converted from
  controller, same routes/shapes), photos (Oscar contract: GET array/POST multipart/DELETE,
  url /photos/files/{fileName}). Gridify paged {items,totalCount,page,pageSize}, camelCase,
  409 conflict-deletes, flat FK ids, litter parent-gender validation (400 {code,...}).
- Scalar replaces Swashbuckle (AddOpenApi/MapOpenApi + MapScalarApiReference at /scalar);
  launchUrl swagger->scalar. GenericRepository/UnitOfWork/Converters deleted; DbContext direct.
- InbreedingService reads real FK props now; pure calculator + 8 tests untouched.

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

GerbilManagerWebAPI/Common/PagedResult.cs

@@ -0,0 +1,30 @@
+using Gridify;
+using Gridify.EntityFramework;
+
+namespace GerbilManagerWebAPI.Common
+{
+    /// <summary>Standard paged list envelope returned by every list endpoint.</summary>
+    public record PagedResult<T>(IReadOnlyList<T> Items, int TotalCount, int Page, int PageSize);
+
+    public static class QueryableExtensions
+    {
+        /// <summary>
+        /// Apply a Gridify query (filter/order/page) to an EF query and project each
+        /// row to a DTO, returning the standard paged envelope. Filter/orderBy names
+        /// are the ENTITY property names (case-insensitive), e.g. "status==Active",
+        /// "orderBy=dateOfBirth", "litterId==...".
+        /// </summary>
+        public static async Task<PagedResult<TDto>> ToPagedResultAsync<TEntity, TDto>(
+            this IQueryable<TEntity> source,
+            GridifyQuery query,
+            Func<TEntity, TDto> map)
+        {
+            query.Page = query.Page <= 0 ? 1 : query.Page;
+            query.PageSize = query.PageSize <= 0 ? 20 : query.PageSize;
+
+            Paging<TEntity> paging = await source.GridifyAsync(query);
+            var items = paging.Data.Select(map).ToList();
+            return new PagedResult<TDto>(items, paging.Count, query.Page, query.PageSize);
+        }
+    }
+}