fix(developers): fix application record creation and approval flow

Fix two bugs preventing developer applications from appearing in SilverDESK:

1. Application creation payload used wrong types - ticketId was parsed as
   int (GetInt32) but SilverDESK expects a Guid string, and appliedRole
   was cast to int but the DTO expects "Tester"/"Developer" strings.

2. Approval provisioning now updates the DeveloperApplication record in
   SilverDESK after Mattermost/Mailcow provisioning, setting status to
   Approved and the correct provisioning flags.

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

BlazorApp/Services/DeveloperApplicationService.cs

@@ -100,7 +100,7 @@ public class DeveloperApplicationService
             {
                 var userId = authResult.GetProperty("user").GetProperty("id").GetString();
                 var ticketResult = await ticketResponse.Content.ReadFromJsonAsync<JsonElement>();
-                var ticketId = ticketResult.GetProperty("id").GetInt32();
+                var ticketId = ticketResult.GetProperty("id").GetString();
 
                 var applicationPayload = new
                 {
@@ -110,7 +110,7 @@ public class DeveloperApplicationService
                     email = application.Email,
                     desiredUsername = application.DesiredUsername,
                     timezone = application.Timezone,
-                    appliedRole = (int)application.Role,
+                    appliedRole = application.Role.ToString(),
                     platforms = application.Platforms,
                     skills = application.Skills ?? "",
                     motivation = application.Motivation,