feat: show Jobs tab for all vendors when no filter selected

- Add /admin/letzshop/jobs API endpoint for all jobs across vendors
- Update list_letzshop_jobs service to support optional vendor_id
- Remove x-if condition from Jobs tab button and panel
- Update JS to use global or vendor-specific endpoint based on selection
- Update jobs table subtitle to show context

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/api/v1/admin/letzshop.py

@@ -702,6 +702,37 @@ def trigger_vendor_sync(
 # ============================================================================
 
 
+@router.get(
+    "/jobs",
+    response_model=LetzshopJobsListResponse,
+)
+def list_all_letzshop_jobs(
+    job_type: str | None = Query(None, description="Filter: import, export, order_sync, historical_import"),
+    status: str | None = Query(None, description="Filter by status"),
+    skip: int = Query(0, ge=0),
+    limit: int = Query(20, ge=1, le=100),
+    db: Session = Depends(get_db),
+    current_admin: User = Depends(get_current_admin_api),
+):
+    """
+    Get unified list of all Letzshop-related jobs across all vendors.
+    Combines product imports, exports, and order syncs.
+    """
+    order_service = get_order_service(db)
+
+    jobs_data, total = order_service.list_letzshop_jobs(
+        vendor_id=None,
+        job_type=job_type,
+        status=status,
+        skip=skip,
+        limit=limit,
+    )
+
+    jobs = [LetzshopJobItem(**job) for job in jobs_data]
+
+    return LetzshopJobsListResponse(jobs=jobs, total=total)
+
+
 @router.get(
     "/vendors/{vendor_id}/jobs",
     response_model=LetzshopJobsListResponse,