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/DTO/Staff/Request/CreateStaffDto.cs

@@ -6,4 +6,6 @@ public class CreateStaffDto
     public string? LastName { get; set; }
     public string? Profession { get; set; }
     public string? Email { get; set; }
+    public string? F4T2NumberApproval { get; set; }
+    public DateOnly F4T2ExpirationDate { get; set; }
 }

PyroFetes/DTO/Staff/Request/UpdateStaffDto.cs

@@ -7,4 +7,6 @@ public class UpdateStaffDto
     public string? LastName { get; set; }
     public string? Profession { get; set; }
     public string? Email { get; set; }
+    public string? F4T2NumberApproval { get; set; }
+    public DateOnly? F4T2ExpirationDate { get; set; }
 }

PyroFetes/DTO/Staff/Response/ReadStaffDto.cs

@@ -7,4 +7,6 @@ public class ReadStaffDto
     public string? LastName { get; set; }
     public string? Profession { get; set; }
     public string? Email { get; set; }
+    public string? F4T2NumberApproval { get; set; }
+    public DateOnly F4T2ExpirationDate { get; set; }
 }