chore: 底部栏高度 28→32px，常量同步更新

src/components/layout/StatusBar.tsx

@@ -23,7 +23,7 @@ export function StatusBar(): React.JSX.Element {
       component="footer"
       sx={{
         flexShrink: 0, display: 'flex', alignItems: 'center',
-        px: 1.5, height: 28, bgcolor: 'background.paper',
+        px: 1.5, height: 32, bgcolor: 'background.paper',
         borderTop: 1, borderColor: 'divider', userSelect: 'none',
       }}
     >

src/lib/constants.ts

@@ -7,8 +7,8 @@
 // ===== 布局尺寸 =====
 
 export const LAYOUT = {
-  HEADER_HEIGHT: 40,
-  STATUS_BAR_HEIGHT: 24,
+  HEADER_HEIGHT: 0, // 已移除顶部栏
+  STATUS_BAR_HEIGHT: 32,
   SIDEBAR_WIDTH: 260,
   DETAIL_WIDTH: 320,
   CHAT_MAX_WIDTH: 768,