ui/app: per-job overlap policy in job dialog and details panel

- job_dialog.go: add overlap-policy widget.Select with "(Use global
  default)" → empty, "skip", and "queue" options; pre-selects the job's
  current value; on save maps the inherit label back to empty string.
- app/format.go: add DisplayOverlapPolicy(job, globalPolicy) — returns
  the policy name when overridden, else "skip/queue (global default)".
- ui/jobs_view.go: add "Overlap policy" detail row updated in
  updateDetails using DisplayOverlapPolicy.
- settings_view.go: rename "Overlap policy" label to "Default overlap
  policy" to clarify it is the global default jobs can override.

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

src/app/format.go

@@ -92,6 +92,16 @@ func DisplayStats(rt *domain.JobRuntime) string {
 		rt.RunCount, rt.FailCount, rt.LastDurationMS, rt.AvgDurationMS, rt.MaxDurationMS)
 }
 
+// DisplayOverlapPolicy formats a job's effective overlap policy for the details
+// panel. When the job has its own policy it is shown as-is; when empty (inherit
+// global), the global default is shown with "(global default)" appended.
+func DisplayOverlapPolicy(job domain.Job, globalPolicy domain.OverlapPolicy) string {
+	if p := domain.OverlapPolicy(strings.TrimSpace(job.OverlapPolicy)); p != "" {
+		return string(p)
+	}
+	return string(globalPolicy) + " (global default)"
+}
+
 // DisplayIndex returns the position of jobIndex in the given slice of indexes,
 // or 0 if not found.
 func DisplayIndex(indexes []int, jobIndex int) int {