yoda: cargo clippy --fix on libcosmic-yoda (115→33 warnings)

Auto-applied clippy lint suggestions across 23 files: collapse
`else { if … }` ladders, drop unneeded `return` statements, remove
needless borrows that were immediately auto-dereffed, swap `iter().next()`
for `first()`, drop redundant `.into()` to the same type, and similar
mechanical cleanups. Behavior is unchanged; the diff is -67 lines net.

The 33 remaining warnings are architectural and need manual attention
(very-complex-type aliases, too-many-arguments on internal helpers,
redundant must_use, needs-is_empty, etc.).

Leyoda 2026 – GPLv3

src/widget/popover.rs

@@ -164,8 +164,8 @@ where
                     shell.capture_event();
                     return;
                 }
-            } else if let Some(on_close) = self.on_close.as_ref() {
-                if matches!(
+            } else if let Some(on_close) = self.on_close.as_ref()
+                && matches!(
                     event,
                     Event::Mouse(mouse::Event::ButtonPressed(_))
                         | Event::Touch(touch::Event::FingerPressed { .. })
@@ -173,7 +173,6 @@ where
                 {
                     shell.publish(on_close.clone());
                 }
-            }
         }
 
         // Hide cursor from background content when modal popup is active