feat(statusbar): isolate action menu on the pill and right-click

Clicking the ISO pill now opens a small menu with Isolate Objects, Hide
Objects and End Isolation instead of ending isolation directly; rows
that don't apply (no selection / nothing hidden) are dimmed. The same
actions are added to the viewport right-click menu.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/ui/statusbar.rs

@@ -177,12 +177,8 @@ impl StatusBar {
         }
         if vis(StatusPill::Isolate) {
             right_status = right_status.push(tip(
-                toggle_pill(
-                    "ISO",
-                    isolation_active,
-                    Message::Command("UNISOLATEOBJECTS".into()),
-                ),
-                "Isolate Objects\nISOLATEOBJECTS / HIDEOBJECTS to hide; click to restore",
+                toggle_pill("ISO", isolation_active, Message::ToggleIsolatePopup),
+                "Isolate Objects\nClick for Isolate / Hide / End",
             ));
         }
         if vis(StatusPill::Vp) && !vp_label.is_empty() {