Aggiunge l'autoscaler streaming con warm spare e kill-switch.

Scala i nodi overflow quando gli slot calano, mantiene una spare a caldo sotto carico e spegne gli idle, disattivabile con STREAM_AUTOSCALE_ENABLED.

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

backend/app/views/admin/stream_nodes/index.html.erb

@@ -4,6 +4,20 @@
   <%= t("admin.stream_nodes.providers", cloud: @cloud_provider, dns: @dns_provider) %>
 </p>
 
+<p class="admin-muted">
+  <%= t(
+        "admin.stream_nodes.autoscale",
+        enabled: (@autoscale_metrics[:enabled] ? "ON" : "OFF"),
+        free: @autoscale_metrics[:free_slots],
+        soft: @autoscale_metrics[:soft_free_slots],
+        spare: @autoscale_metrics[:spare_ready],
+        warm: @autoscale_metrics[:warm_spare_min],
+        overflow: @autoscale_metrics[:overflow_nodes],
+        max: @autoscale_metrics[:max_overflow_nodes],
+        kind: @autoscale_metrics[:kind]
+      ) %>
+</p>
+
 <p>
   <%= button_to t("admin.stream_nodes.provision_lab"), admin_stream_nodes_path, method: :post, params: { kind: "lab" }, class: "admin-btn" %>
   <% if @hetzner_configured %>