Refactor web build process and update documentation

- Removed Node.js build artifacts from .gitignore and adjusted Makefile to reflect changes in web UI build process, now using server-rendered Go templates instead of React.
- Updated README to clarify the new web UI architecture and output formats, emphasizing the removal of the Node.js build step.
- Added a command to set the number of frames per render task in manager configuration, enhancing user control over rendering settings.
- Improved Gitea workflow by removing unnecessary npm install step, streamlining the CI process.

internal/manager/manager.go

@@ -59,6 +59,7 @@ type Manager struct {
 	secrets *authpkg.Secrets
 	storage *storage.Storage
 	router  *chi.Mux
+	ui      *uiRenderer
 
 	// WebSocket connections
 	wsUpgrader websocket.Upgrader
@@ -125,10 +126,24 @@ type ClientConnection struct {
 type UploadSession struct {
 	SessionID string
 	UserID    int64
+	TempDir   string
 	Progress  float64
 	Status    string // "uploading", "processing", "extracting_metadata", "creating_context", "completed", "error"
+	Phase     string // "upload", "processing", "ready", "error", "action_required"
 	Message   string
 	CreatedAt time.Time
+	// Result fields set when Status is "completed" (for async processing)
+	ResultContextArchive    string
+	ResultMetadata          interface{} // *types.BlendMetadata when set
+	ResultMainBlendFile     string
+	ResultFileName          string
+	ResultFileSize          int64
+	ResultZipExtracted      bool
+	ResultExtractedFilesCnt int
+	ResultMetadataExtracted bool
+	ResultMetadataError     string   // set when Status is "completed" but metadata extraction failed
+	ErrorMessage            string   // set when Status is "error"
+	ResultBlendFiles        []string // set when Status is "select_blend" (relative paths for user to pick)
 }
 
 // NewManager creates a new manager server
@@ -137,6 +152,10 @@ func NewManager(db *database.DB, cfg *config.Config, auth *authpkg.Auth, storage
 	if err != nil {
 		return nil, fmt.Errorf("failed to initialize secrets: %w", err)
 	}
+	ui, err := newUIRenderer()
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize UI renderer: %w", err)
+	}
 
 	s := &Manager{
 		db:        db,
@@ -145,6 +164,7 @@ func NewManager(db *database.DB, cfg *config.Config, auth *authpkg.Auth, storage
 		secrets:   secrets,
 		storage:   storage,
 		router:    chi.NewRouter(),
+		ui:        ui,
 		startTime: time.Now(),
 		wsUpgrader: websocket.Upgrader{
 			CheckOrigin:     checkWebSocketOrigin,
@@ -450,6 +470,7 @@ func (w *gzipResponseWriter) WriteHeader(statusCode int) {
 func (s *Manager) setupRoutes() {
 	// Health check endpoint (unauthenticated)
 	s.router.Get("/api/health", s.handleHealthCheck)
+	s.setupUIRoutes()
 
 	// Public routes (with stricter rate limiting for auth endpoints)
 	s.router.Route("/api/auth", func(r chi.Router) {
@@ -477,6 +498,7 @@ func (s *Manager) setupRoutes() {
 		})
 		r.Post("/", s.handleCreateJob)
 		r.Post("/upload", s.handleUploadFileForJobCreation) // Upload before job creation
+		r.Get("/upload/status", s.handleUploadStatus)       // Poll upload processing status (session_id query param)
 		r.Get("/", s.handleListJobs)
 		r.Get("/summary", s.handleListJobsSummary)
 		r.Post("/batch", s.handleBatchGetJobs)
@@ -487,6 +509,7 @@ func (s *Manager) setupRoutes() {
 		r.Get("/{id}/files", s.handleListJobFiles)
 		r.Get("/{id}/files/count", s.handleGetJobFilesCount)
 		r.Get("/{id}/context", s.handleListContextArchive)
+		r.Get("/{id}/files/exr-zip", s.handleDownloadEXRZip)
 		r.Get("/{id}/files/{fileId}/download", s.handleDownloadJobFile)
 		r.Get("/{id}/files/{fileId}/preview-exr", s.handlePreviewEXR)
 		r.Get("/{id}/video", s.handleStreamVideo)
@@ -522,7 +545,6 @@ func (s *Manager) setupRoutes() {
 				r.Delete("/{id}", s.handleDeleteRunnerAPIKey)
 			})
 			r.Get("/", s.handleListRunnersAdmin)
-			r.Post("/{id}/verify", s.handleVerifyRunner)
 			r.Delete("/{id}", s.handleDeleteRunner)
 		})
 		r.Route("/users", func(r chi.Router) {
@@ -555,6 +577,7 @@ func (s *Manager) setupRoutes() {
 				return http.HandlerFunc(s.runnerAuthMiddleware(next.ServeHTTP))
 			})
 			r.Get("/blender/download", s.handleDownloadBlender)
+			r.Get("/jobs/{jobId}/status", s.handleGetJobStatusForRunner)
 			r.Get("/jobs/{jobId}/files", s.handleGetJobFilesForRunner)
 			r.Get("/jobs/{jobId}/metadata", s.handleGetJobMetadataForRunner)
 			r.Get("/files/{jobId}/{fileName}", s.handleDownloadFileForRunner)
@@ -564,8 +587,8 @@ func (s *Manager) setupRoutes() {
 	// Blender versions API (public, for job submission page)
 	s.router.Get("/api/blender/versions", s.handleGetBlenderVersions)
 
-	// Serve static files (embedded React app with SPA fallback)
-	s.router.Handle("/*", web.SPAHandler())
+	// Static assets for server-rendered UI.
+	s.router.Handle("/assets/*", web.StaticHandler())
 }
 
 // ServeHTTP implements http.Handler