Aggiunge copertina sponsor custom solo Premium Full, con override in wizard e slate sui nodi di streaming.

Permette upload da portale e app con ereditarietà partita→squadra→società, generazione MP4 via ffmpeg e distribuzione su home lab e nodi CPX per pause e assenza segnale.

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

backend/app/services/streams/cover_slate_paths.rb

@@ -0,0 +1,30 @@
+module Streams
+  class CoverSlatePaths
+    def self.slates_custom_root
+      ENV.fetch("MEDIAMTX_SLATES_CUSTOM_DIR", "/slates/custom")
+    end
+
+    def self.filename_for(record)
+      return nil unless record.cover_slate.attached?
+
+      digest = record.cover_slate.blob.checksum
+      prefix = record.class.name.underscore
+      "#{prefix}-#{record.id}-#{digest}.mp4"
+    end
+
+    def self.expected_path(record)
+      name = filename_for(record)
+      return nil if name.blank?
+
+      File.join(slates_custom_root, name)
+    end
+
+    def self.local_path_for(record)
+      path = expected_path(record)
+      return nil if path.blank?
+      return path if File.exist?(path)
+
+      nil
+    end
+  end
+end