Fix viewport input leaking through dialogs

Use egui pointer ownership for viewport navigation and picking, view-cube
interaction, and sketch-dimension hover. Cover scrolling, model selection,
and cube interaction under floating dialogs, including after they close.
Shield constraint glyph and move-gizmo highlights from overlapping UI too.

Clear strict Clippy warnings and use the same saved path in the recent-file
scenario on Windows and Unix.

Fixes #87

crates/ui-egui/src/dialogs.rs

@@ -1855,7 +1855,7 @@ pub fn show(app: &mut SolveApp, ctx: &egui::Context) {
             Err(e) => d.error = Some(e),
         }
     }
-    if !(keep && !cancel) {
+    if !keep || cancel {
         crate::dialogs_motion::closed(app, &mut d, applied);
     }
     if keep && !cancel {