v0.57.0: stable host-storage list + per-app Tier-2 config panel

Part A of the UI-fixes/storage-spike spec.

A1: enrichHostStorageTargets sorts /api/host-metrics storage_targets
server-side and attaches friendly Hungarian labels + purpose, fixing the
#host-storage-bars reorder-on-poll bug. Display labels only — PVE storage
ids are never renamed.

A2: new GET/POST /stacks/{name}/backup Tier-2 config panel; the "2. mentés"
Beállítás button is repointed there from the dead-end deploy page. Customer
can pin a target drive or disable Tier 2; preference is preserved across the
runner's status writes. Always visible (single-SSD + non-HDD apps included).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

controller/internal/web/server.go

@@ -263,6 +263,12 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		name := strings.TrimPrefix(path, "/stacks/")
 		name = strings.TrimSuffix(name, "/deploy")
 		s.deployHandler(w, r, name)
+	case strings.HasPrefix(path, "/stacks/") && strings.HasSuffix(path, "/backup") && r.Method == http.MethodGet:
+		name := strings.TrimSuffix(strings.TrimPrefix(path, "/stacks/"), "/backup")
+		s.tier2ConfigPageHandler(w, r, name)
+	case strings.HasPrefix(path, "/stacks/") && strings.HasSuffix(path, "/backup") && r.Method == http.MethodPost:
+		name := strings.TrimSuffix(strings.TrimPrefix(path, "/stacks/"), "/backup")
+		s.tier2ConfigSaveHandler(w, r, name)
 	case path == "/import":
 		s.importPageHandler(w, r)
 	case path == "/static/style.css":