feat(activity): merge CAD + render jobs into unified timeline

- Single chronological list sorted by updated_at (newest first)
- Type badges distinguish CAD processing (FileCode2) from Render jobs (Image)
- Render job rows now link directly to the order (/orders/:id)
- Remove separate "Render Jobs" and "CAD File Processing" sections
- Stat cards simplified to 4: CAD active/failed + Render active/failed
- Backend: add order_id to RenderJobEntry response
- Frontend: add order_id to RenderJobEntry interface, remove flamenco_job_id

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/worker.ts

@@ -37,12 +37,12 @@ export interface CadActivityEntry {
 
 export interface RenderJobEntry {
   order_line_id: string
+  order_id: string | null
   order_number: string | null
   product_name: string | null
   output_type_name: string | null
   render_status: 'processing' | 'completed' | 'failed' | string
   render_backend_used: string | null
-  flamenco_job_id: string | null
   render_started_at: string | null
   render_completed_at: string | null
   updated_at: string