Fix FastEndpoints/Swagger wiring and missing required fields in DTOs

- Register FastEndpoints, SwaggerDocument, DbContext in Program.cs
- Add DbContextOptions constructor to PyroFetesDbContext
- Add CityId to Show DTOs and endpoints (NOT NULL in DB)
- Add F4T2NumberApproval/F4T2ExpirationDate to Staff DTOs and endpoints
- Simplify DeleteShow to rely on DB cascade instead of manual includes
- Default NOT NULL string fields to empty string on create

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

PyroFetes/Endpoints/Show/UpdateShowEndpoint.cs

@@ -34,11 +34,8 @@ public class UpdateShowEndpoint(PyroFetesDbContext pyroFetesDbContext) : Endpoin
         show.Place = req.Place ?? show.Place;
         show.Description = req.Description ?? show.Description;
         show.PyrotechnicImplementationPlan = req.PyrotechnicImplementationPlan ?? show.PyrotechnicImplementationPlan;
-        
-        if (req.Date.HasValue)
-        {
-            show.Date = DateOnly.FromDateTime(req.Date.Value);
-        }
+        if (req.CityId.HasValue) show.CityId = req.CityId.Value;
+        if (req.Date.HasValue) show.Date = DateOnly.FromDateTime(req.Date.Value);
 
         await pyroFetesDbContext.SaveChangesAsync(ct);
 
@@ -49,7 +46,8 @@ public class UpdateShowEndpoint(PyroFetesDbContext pyroFetesDbContext) : Endpoin
             Place = show.Place,
             Description = show.Description,
             PyrotechnicImplementationPlan = show.PyrotechnicImplementationPlan,
-            Date = show.Date.HasValue ? show.Date.Value.ToDateTime(TimeOnly.MinValue) : null
+            Date = show.Date.HasValue ? show.Date.Value.ToDateTime(TimeOnly.MinValue) : null,
+            CityId = show.CityId
         };
 
         await Send.OkAsync(result, ct);