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/Endpoints/LitterEndpoints.cs

@@ -0,0 +1,91 @@
+using GerbilManagerWebAPI.Common;
+using GerbilManagerWebAPI.Dtos;
+using GerbilManagerWebAPI.Models;
+using Gridify;
+using Microsoft.AspNetCore.Http.HttpResults;
+using Microsoft.EntityFrameworkCore;
+
+namespace GerbilManagerWebAPI.Endpoints
+{
+    public static class LitterEndpoints
+    {
+        public static IEndpointRouteBuilder MapLitterEndpoints(this IEndpointRouteBuilder app)
+        {
+            var group = app.MapGroup("/litters").WithTags("Litters");
+
+            // GET /litters  (Gridify: date range + orderBy=date supported on the DateOnly column)
+            group.MapGet("/", async ([AsParameters] GridifyQuery query, ApplicationContext db) =>
+                TypedResults.Ok(await db.Litters.AsNoTracking().ToPagedResultAsync(query, ToDto)));
+
+            group.MapGet("/{id:guid}", async Task<Results<Ok<LitterDto>, NotFound>> (Guid id, ApplicationContext db) =>
+            {
+                var l = await db.Litters.AsNoTracking().FirstOrDefaultAsync(x => x.Id == id);
+                return l is null ? TypedResults.NotFound() : TypedResults.Ok(ToDto(l));
+            });
+
+            group.MapPost("/", async Task<Results<Created<LitterDto>, BadRequest<ParentGenderError>>> (LitterInput input, ApplicationContext db) =>
+            {
+                var err = await ValidateParents(db, input.FatherId, input.MotherId);
+                if (err is not null) return TypedResults.BadRequest(err);
+
+                var l = new Litter { Id = Guid.NewGuid(), Name = input.Name, Date = input.Date };
+                Apply(l, input);
+                db.Litters.Add(l);
+                await db.SaveChangesAsync();
+                return TypedResults.Created($"/litters/{l.Id}", ToDto(l));
+            });
+
+            group.MapPut("/{id:guid}", async Task<Results<NoContent, NotFound, BadRequest<ParentGenderError>>> (Guid id, LitterInput input, ApplicationContext db) =>
+            {
+                var l = await db.Litters.FirstOrDefaultAsync(x => x.Id == id);
+                if (l is null) return TypedResults.NotFound();
+                var err = await ValidateParents(db, input.FatherId, input.MotherId);
+                if (err is not null) return TypedResults.BadRequest(err);
+                l.Name = input.Name;
+                l.Date = input.Date;
+                Apply(l, input);
+                await db.SaveChangesAsync();
+                return TypedResults.NoContent();
+            });
+
+            group.MapDelete("/{id:guid}", async Task<Results<NoContent, NotFound>> (Guid id, ApplicationContext db) =>
+            {
+                var l = await db.Litters.FirstOrDefaultAsync(x => x.Id == id);
+                if (l is null) return TypedResults.NotFound();
+                db.Litters.Remove(l);
+                await db.SaveChangesAsync();
+                return TypedResults.NoContent();
+            });
+
+            return app;
+        }
+
+        // father must not be female; mother must not be male (unknown is allowed).
+        private static async Task<ParentGenderError?> ValidateParents(ApplicationContext db, Guid? fatherId, Guid? motherId)
+        {
+            var father = fatherId is Guid f ? await db.Gerbils.AsNoTracking().FirstOrDefaultAsync(x => x.Id == f) : null;
+            var mother = motherId is Guid m ? await db.Gerbils.AsNoTracking().FirstOrDefaultAsync(x => x.Id == m) : null;
+            if (father?.Gender == Gender.female || mother?.Gender == Gender.male)
+            {
+                return new ParentGenderError("InvalidParentGender",
+                    father?.Gender ?? Gender.unknown, mother?.Gender ?? Gender.unknown);
+            }
+            return null;
+        }
+
+        private static void Apply(Litter l, LitterInput i)
+        {
+            l.TotalBorn = i.TotalBorn;
+            l.FatherId = i.FatherId;
+            l.MotherId = i.MotherId;
+            l.ExpectedGoHomeDate = i.ExpectedGoHomeDate;
+            l.Notes = i.Notes;
+        }
+
+        private static LitterDto ToDto(Litter l) => new(
+            l.Id, l.Name, l.Date, l.TotalBorn, l.FatherId, l.MotherId, l.ExpectedGoHomeDate, l.Notes);
+    }
+
+    /// <summary>400 body for a father×mother gender mismatch; frontend localises by Code.</summary>
+    public record ParentGenderError(string Code, Gender FatherGender, Gender MotherGender);
+}