ui: remove Center button from header (center behavior kept for Restore)

src/ui.tsx

@@ -6,8 +6,7 @@ import {
   VerticalSpace,
   IconButton,
   IconExpand24,
-  IconCollapse24,
-  IconDockToSide24
+  IconCollapse24
 } from '@create-figma-plugin/ui'
 import { emit, on } from '@create-figma-plugin/utilities'
 import { h, Fragment } from 'preact'
@@ -286,12 +285,6 @@ function Plugin () {
       <Container space="medium" style={{ height: '100%', display: 'flex', flexDirection: 'column' }}>
         <div style={{ display: 'flex', justifyContent: 'flex-end', alignItems: 'center' }}>
           <div style={{ display: 'flex', gap: '4px', alignItems: 'center' }}>
-            <IconButton
-              title="Center window (50% viewport)"
-              onClick={function () { dockWindow('center') }}
-            >
-              <IconDockToSide24 />
-            </IconButton>
             <IconButton
               title={isMaximized ? 'Restore window' : 'Maximize window'}
               onClick={toggleWindowSize}