Club come entità principale, branding e fix infrastruttura streaming.

Introduce clubs con abbonamento, branding Active Storage e flusso registrazione società; corregge healthcheck MediaMTX (immagine distroless) e allinea dominio produzione matchlivetv.it.

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

backend/app/models/subscription.rb

@@ -2,11 +2,11 @@ class Subscription < ApplicationRecord
   STATUSES = %w[active trialing past_due canceled incomplete].freeze
   ACTIVE_STATUSES = %w[active trialing].freeze
 
-  belongs_to :team
+  belongs_to :club
   belongs_to :plan
 
   validates :status, inclusion: { in: STATUSES }
-  validates :team_id, uniqueness: true
+  validates :club_id, uniqueness: true
 
   scope :active, -> { where(status: ACTIVE_STATUSES) }