M5: main's colour-submenu test builds an Annotation with no pop-up (#2137)

main's #4066 test (the context menu's colour submenu keeps its picker
open) builds a pdfcraft_render::Annotation without the popup field this
branch adds, so the ui-egui tests stopped compiling after the rebase.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0175FWj4xFhMhSH3UpMU8DSC

crates/ui-egui/src/comments.rs

@@ -2788,6 +2788,7 @@ mod tests {
                 fill_sign: false,
                 points: Vec::new(),
                 no_rotate: false,
+                popup: None,
             }],
             ..Default::default()
         };