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>

backend/app/api/routers/worker.py

@@ -33,6 +33,7 @@ class CadActivityEntry(BaseModel):
 
 class RenderJobEntry(BaseModel):
     order_line_id: str
+    order_id: str | None
     order_number: str | None
     product_name: str | None
     output_type_name: str | None
@@ -134,6 +135,7 @@ async def get_worker_activity(
     for rl in render_lines:
         render_entries.append(RenderJobEntry(
             order_line_id=str(rl.id),
+            order_id=str(rl.order_id) if rl.order_id else None,
             order_number=rl.order.order_number if rl.order else None,
             product_name=rl.product.name if rl.product else None,
             output_type_name=rl.output_type.name if rl.output_type else None,