chore(core): adjust tab height and windows control, remove input background (#12862)

close AF-2697, AF-2696

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

- **Style**
- Made the AI chat input field background transparent for improved
visual consistency.
- Reduced the size of window app control buttons and removed extra
padding from the close button.
- Decreased the height of tabs and the width of the window app controls
placeholder for a more compact layout.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/frontend/core/src/components/pure/header/style.css.tsx

@@ -63,17 +63,13 @@ export const windowAppControl = style({
   WebkitAppRegion: 'no-drag',
   cursor: 'pointer',
   display: 'inline-flex',
-  width: '52px',
-  height: '52px',
+  width: '40px',
+  height: '40px',
   alignItems: 'center',
   justifyContent: 'center',
   borderRadius: '0',
   color: 'var(--affine-icon-color)',
   selectors: {
-    '&[data-type="close"]': {
-      width: '56px',
-      paddingRight: '5px',
-    },
     '&[data-type="close"]:hover': {
       background: 'var(--affine-windows-close-button)',
       color: 'var(--affine-pure-white)',