yoda: warning cleanup sweep (dead code + clippy --fix) (squashed)

Squash of 4 yoda commits:
- 84437e21 yoda: libcosmic-yoda dead-code purge (14->0 warnings)
- 999db0a4 yoda: cosmic-theme cleanup (4->0 warnings) — workspace at 0 warnings total
- 4743bb8e yoda: cargo clippy --fix on libcosmic-yoda (115->33 warnings)
- 675f3b59 chore: reduce local stack warnings

src/widget/menu/menu_inner.rs

@@ -1522,14 +1522,13 @@ where
             .is_some_and(|i| *i != new_index && !active_menu[*i].children.is_empty());
 
         #[cfg(all(feature = "multi-window", feature = "wayland", target_os = "linux", feature = "surface-message"))]
-        if matches!(WINDOWING_SYSTEM.get(), Some(WindowingSystem::Wayland)) && remove {
-            if let Some(id) = state.popup_id.remove(&menu.window_id) {
+        if matches!(WINDOWING_SYSTEM.get(), Some(WindowingSystem::Wayland)) && remove
+            && let Some(id) = state.popup_id.remove(&menu.window_id) {
                 state.active_root.truncate(menu.depth + 1);
                 shell.publish((menu.on_surface_action.as_ref().unwrap())({
                     crate::surface::action::destroy_popup(id)
                 }));
             }
-        }
         let item = &active_menu[new_index];
         // set new index
         let old_index = last_menu_state.index.replace(new_index);