Add hover tooltips on job list rows showing description and PO number

Adds CustomerPO to JobListDto (maps by convention), then builds a
Bootstrap tooltip per row with description · PO: xxx, skipping blank
fields. Rows with neither get no tooltip. Helps identify jobs at a
glance without opening the details page.

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

src/PowderCoating.Application/DTOs/Job/JobDtos.cs

@@ -113,6 +113,7 @@ public class JobListDto
 
     public string? CustomerEmail { get; set; }
     public bool CustomerNotifyByEmail { get; set; } = true;
+    public string? CustomerPO { get; set; }
     public DateTime? ScheduledDate { get; set; }
     public DateTime? DueDate { get; set; }
     public decimal FinalPrice { get; set; }