Aggiunge annunci in-app/sito, contatti e migliora UI copertina sul portale.

Include admin/API/banner nativi, form contatti e reset copertina standard con layout edit più ampio.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models/admin_account.rb

@@ -2,6 +2,7 @@ class AdminAccount < ApplicationRecord
   include PasswordComplexity
 
   has_secure_password
+  has_many :app_announcements, foreign_key: :created_by_admin_id, dependent: :nullify, inverse_of: :created_by_admin
 
   validates :username, presence: true, uniqueness: true
 end