Simplify session lifecycle and MCP cleanup

internal/app/palette.go

@@ -115,7 +115,7 @@ func (p *paletteState) allItems() []paletteItem {
 		if c.Kind == KindAgent && c.Status() != StatusRunning {
 			continue
 		}
-		label := "Switch to " + c.Name
+		label := "Switch to " + c.DisplayName()
 		hint := strings.Join(c.Argv, " ")
 		if c.ID == p.focused {
 			label = "• " + label + " (current)"
@@ -153,7 +153,7 @@ func (p *paletteState) allItems() []paletteItem {
 			continue
 		}
 		out = append(out, paletteItem{
-			label:  "Kill " + c.Name,
+			label:  "Kill " + c.DisplayName(),
 			hint:   "SIGTERM " + strings.Join(c.Argv, " "),
 			action: paletteAction{kind: "kill", childID: c.ID},
 		})