ui: add header/footer padding via --space-8 / --space-4 tokens

src/ui.tsx

@@ -322,7 +322,7 @@ function Plugin () {
     <div className="plugin-root" style={{ position: 'relative', width: '100%', height: '100%' }}>
       <Container space="medium" style={{ height: '100%', display: 'flex', flexDirection: 'column' }}>
         {/* Header — navigation bar */}
-        <header style={{ display: 'flex', alignItems: 'center', flex: '0 0 auto' }}>
+        <header style={{ display: 'flex', alignItems: 'center', flex: '0 0 auto', padding: 'var(--space-8)' }}>
           <Text style={{ fontSize: '13px', fontWeight: 600 }}>Settings</Text>
           <nav style={{ display: 'flex', alignItems: 'center', gap: 'var(--space-4)', marginLeft: 'auto' }}>
             <IconButton title="Stub action" onClick={function () {}}>
@@ -349,7 +349,7 @@ function Plugin () {
         </main>
         {/* Footer — status bar */}
         <Divider />
-        <footer style={{ display: 'flex', alignItems: 'center', flex: '0 0 auto' }}>
+        <footer style={{ display: 'flex', alignItems: 'center', flex: '0 0 auto', padding: 'var(--space-4)' }}>
           <Muted style={{ fontSize: '11px' }}>Version {PLUGIN_VERSION}</Muted>
         </footer>
       </Container>