Finalize reporting, KPIs, and station barcode image on activation

- Include per-job KPIs in CSV reports:
  - Reuse existing calculate_kpis([job.id]) to add the same KPI values
    shown on the admin Reporting page into each job's CSV.
  - Adds overall throughput and output, and per-station processing
    time, throughput, output, and waiting time (non-entry stations).
- Show barcode image for the current station step when a job is
  activated at that station (kiosk/worker view).
- Update barcode_service.py with BytesIO import for image handling.
- Adjust routes and templates (job_detail, worker_kiosk) to support
  the updated reporting flow and related UI behavior.