Aggiunge registry nodi stream e provisioning Hetzner/lab per lo scale-out.

Prepara l'architettura multi-nodo (MediaMTX+ffmpeg) con assignment URL per sessione, admin di provision/drain e provider Cloud/DNS astratti verso mltv-stream.net.

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

backend/app/services/streams/cloud_providers/local_lab.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Streams
+  module CloudProviders
+    # Lab senza API Proxmox: simula create/destroy e riusa MediaMTX home per i path.
+    # Utile per testare registry, assignment e admin senza secondi host.
+    class LocalLab < Base
+      def create_node(name:, labels: {})
+        Instance.new(
+          id: "sim-#{name}",
+          name: name,
+          public_ip: labels[:public_ip].presence || "127.0.0.1",
+          private_ip: labels[:private_ip].presence || "127.0.0.1",
+          status: "running",
+          raw: { simulated: true, labels: labels }
+        )
+      end
+
+      def destroy_node(instance_id)
+        true
+      end
+
+      def list_nodes(labels: {})
+        StreamNode.where(provider: "local", role: "lab").map do |node|
+          Instance.new(
+            id: node.provider_instance_id,
+            name: node.slug,
+            public_ip: node.metadata["public_ip"],
+            private_ip: node.metadata["private_ip"],
+            status: node.status == "ready" ? "running" : node.status,
+            raw: node.metadata
+          )
+        end
+      end
+
+      def wait_until_running(instance_id, timeout: 120)
+        Instance.new(id: instance_id, name: instance_id, status: "running")
+      end
+
+      def public_ip(instance_id)
+        "127.0.0.1"
+      end
+    end
+  end
+end