Admin protetto, dashboard KPI e aggiornamenti sito marketing.

Login admin con cambio password, metriche server (CPU/RAM/disco/banda), grafici e statistiche streaming; sezione piani ridimensionata.

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

backend/app/helpers/admin_helper.rb

@@ -0,0 +1,22 @@
+module AdminHelper
+  def format_bytes(bytes)
+    return "—" if bytes.nil?
+
+    units = %w[B KB MB GB TB]
+    size = bytes.to_f
+    unit = units.shift
+    while size >= 1024 && units.any?
+      size /= 1024
+      unit = units.shift
+    end
+    "#{size.round(size >= 10 ? 0 : 1)} #{unit}"
+  end
+
+  def format_duration_minutes(minutes)
+    return "0 min" if minutes.to_i <= 0
+
+    hours = minutes / 60
+    mins = minutes % 60
+    hours.positive? ? "#{hours}h #{mins}m" : "#{mins} min"
+  end
+end