chore: drop the global popovers-registry write — the registry is deleted (Phase 6ae)

The write-only widget::popovers registry (its engine readers went with the
popup path in 6x) is deleted from cce-ui; this was its last clear() call.

Co-Authored-By: Claude Fable 5 <[email protected]>

 src/main.rs | 1 -
 1 file changed, 1 deletion(-)

diff --git a/src/main.rs b/src/main.rs
index 2ac105a..a4db777 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1066,7 +1066,6 @@ impl Application for GraphApp {
         // quads — is built here. Widget text comes from the paint walk (Graph's node names
         // through its per-label hatch, the control panel via the 6i container-text fix).
         self.ui_context.clear_popovers();
-        cce_ui::widget::popovers::clear();
 
         let is_first_layout = !self.widgets_registered;
         if !self.widgets_registered {