button: Fix Button text to align vertical center. (#286)

<img width="1188" alt="image"
src="https://github.com/user-attachments/assets/084727c3-5822-4325-9bbf-374b357b670f">

The point is add `.font_family(".SystemUIFont")` to root view.

crates/app/src/story_workspace.rs

@@ -284,6 +284,7 @@ impl Render for StoryWorkspace {
         let notifications_count = cx.notifications().len();
 
         div()
+            .font_family(".SystemUIFont")
             .relative()
             .size_full()
             .flex()

crates/ui/src/button.rs

@@ -314,13 +314,6 @@ impl RenderOnce for Button {
             _ => self.size,
         };
 
-        // Hotfix the font vertical center for macOS.
-        let text_offset_top = if cfg!(target_os = "windows") {
-            px(0.)
-        } else {
-            px(2.)
-        };
-
         self.base
             .id(self.id)
             .flex()
@@ -443,13 +436,7 @@ impl RenderOnce for Button {
                         )
                     })
                     .when_some(self.label, |this, label| {
-                        this.child(
-                            div()
-                                .flex_none()
-                                .mt(text_offset_top)
-                                .line_height(relative(1.))
-                                .child(label),
-                        )
+                        this.child(div().flex_none().line_height(relative(1.)).child(label))
                     })
                     .children(self.children)
             })