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/controllers/concerns/branding_attachments.rb

@@ -0,0 +1,16 @@
+module BrandingAttachments
+  extend ActiveSupport::Concern
+
+  private
+
+  def attach_branding_logo(record)
+    file = params.dig(:branding, :logo_file)
+    record.logo_file.attach(file) if file.present?
+  end
+
+  def normalize_hex_color(value, fallback)
+    v = value.to_s.strip
+    v = "##{v}" if v.match?(/\A[0-9A-Fa-f]{6}\z/)
+    v.match?(Brandable::HEX_COLOR) ? v : fallback
+  end
+end