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/runner/api/manager.go

@@ -196,7 +196,8 @@ type NextJobTaskInfo struct {
 	TaskID   int64                `json:"task_id"`
 	JobID    int64                `json:"job_id"`
 	JobName  string               `json:"job_name"`
-	Frame    int                  `json:"frame"`
+	Frame    int                  `json:"frame"`     // frame start (inclusive)
+	FrameEnd int                  `json:"frame_end"` // frame end (inclusive); same as Frame for single-frame
 	TaskType string               `json:"task_type"`
 	Metadata *types.BlendMetadata `json:"metadata,omitempty"`
 }
@@ -315,6 +316,28 @@ func (m *ManagerClient) GetJobMetadata(jobID int64) (*types.BlendMetadata, error
 	return &metadata, nil
 }
 
+// GetJobStatus retrieves the current status of a job.
+func (m *ManagerClient) GetJobStatus(jobID int64) (types.JobStatus, error) {
+	path := fmt.Sprintf("/api/runner/jobs/%d/status?runner_id=%d", jobID, m.runnerID)
+	resp, err := m.Request("GET", path, nil)
+	if err != nil {
+		return "", err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		body, _ := io.ReadAll(resp.Body)
+		return "", fmt.Errorf("failed to get job status: %s", string(body))
+	}
+
+	var job types.Job
+	if err := json.NewDecoder(resp.Body).Decode(&job); err != nil {
+		return "", err
+	}
+
+	return job.Status, nil
+}
+
 // JobFile represents a file associated with a job.
 type JobFile struct {
 	ID       int64  `json:"id"`