feat(applications): drag-to-reorder on the public site

Editors can now control the order applications appear in, the same way they
already reorder Hero slides.

- Application gains an `order Int @default(0)` column (additive migration
  20260605120000_add_application_order, IF NOT EXISTS, safe for deploy) plus
  an (isActive, order) index.
- New reorderApplications(orderedSlugs) server action — single $transaction
  renumbering, mirrors reorderHeroSlides.
- HQ applications panel: rows are now draggable by a grip handle (HTML5 DnD,
  optimistic local reorder, persisted on drop, toast feedback).
- All public-facing queries now order by [order asc, createdAt asc]: home
  ApplicationsDashboard + GlobalOperations, the footer apps list, and the
  HQ list itself. Existing rows default to 0 so current order is preserved
  until the editor drags something.

Verified: production build compiles, TypeScript clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

prisma/schema.prisma

@@ -89,6 +89,9 @@ model Application {
   dashboardMetricsJson String?  @default("[]")
   isActive        Boolean  @default(true) // 🔥 NUEVO: Para poder ocultarlas
 
+  // 🔥 NUEVO: Orden manual para drag-to-reorder en el frontend (como HeroSlide)
+  order           Int      @default(0)
+
   // 🌍 MOTOR DE TRADUCCIONES
   translationsJson String?  @default("{}")
 
@@ -97,6 +100,7 @@ model Application {
 
   @@index([isActive])
   @@index([category])
+  @@index([isActive, order])
 }
 
 // ------------------------------------------------------