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/club.rb

@@ -0,0 +1,27 @@
+class Club < ApplicationRecord
+  include Brandable
+
+  has_many :club_memberships, dependent: :destroy
+  has_many :users, through: :club_memberships
+  has_many :teams, dependent: :destroy
+  has_one :subscription, dependent: :destroy
+
+  validates :name, presence: true
+  validates :sport, presence: true
+  validates :primary_color, presence: true
+  validates :secondary_color, presence: true
+
+  def owner
+    club_memberships.find_by(role: "owner")&.user
+  end
+
+  def owned_by?(user)
+    club_memberships.exists?(user: user, role: "owner")
+  end
+
+  private
+
+  def branding_parent
+    nil
+  end
+end