Add دندانپزشک + پرستار سالمندان roles (idempotent ensure on startup)

Roles were only seeded on a fresh DB, so existing deployments never got
new ones. Introduced a canonical role list + EnsureRolesAsync that runs on
every startup and inserts any missing role — so production picks up the two
new roles without a manual step. Original 7 keep their order/ids; the two
new roles are appended (sort 8-9).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/JobsMedical.Web/Program.cs

@@ -94,7 +94,8 @@ using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
     db.Database.Migrate();
-    await SeedData.SeedReferenceAsync(db);   // cities/roles/districts always
+    await SeedData.SeedReferenceAsync(db);   // cities/districts on first run
+    await SeedData.EnsureRolesAsync(db);     // add any missing roles (idempotent, existing DBs too)
     // Demo board in Development, or whenever the admin has turned Demo Mode on.
     var st = await scope.ServiceProvider
         .GetRequiredService<JobsMedical.Web.Services.Scraping.SettingsService>().GetAsync();