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/Staff/UpdateStaffEndpoint.cs

@@ -22,10 +22,13 @@ public class UpdateStaffEndpoint(PyroFetesDbContext pf3DbContext) : Endpoint<Upd
             return;
         }
 
-        staff.FirstName = req.FirstName;
-        staff.LastName = req.LastName;
-        staff.Profession = req.Profession;
-        staff.Email = req.Email;
+        staff.FirstName = req.FirstName ?? staff.FirstName;
+        staff.LastName = req.LastName ?? staff.LastName;
+        staff.Profession = req.Profession ?? staff.Profession;
+        staff.Email = req.Email ?? staff.Email;
+        staff.F4T2NumberApproval = req.F4T2NumberApproval ?? staff.F4T2NumberApproval;
+        if (req.F4T2ExpirationDate.HasValue)
+            staff.F4T2ExpirationDate = req.F4T2ExpirationDate.Value;
 
         await pf3DbContext.SaveChangesAsync(ct);
 
@@ -35,7 +38,9 @@ public class UpdateStaffEndpoint(PyroFetesDbContext pf3DbContext) : Endpoint<Upd
             FirstName = staff.FirstName,
             LastName = staff.LastName,
             Profession = staff.Profession,
-            Email = staff.Email
+            Email = staff.Email,
+            F4T2NumberApproval = staff.F4T2NumberApproval,
+            F4T2ExpirationDate = staff.F4T2ExpirationDate
         };
 
         await Send.OkAsync(result, ct);