Fix draft item styling based on feedback

- Add border and shadow to draft cards
- Remove trash button, move delete to overflow menu prompt
- Remove size differences for thread posts (same avatar/text size)
- Add spacing between header and first draft item
- Change prompt wording to "Discard draft"

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/view/com/util/EmptyState.tsx

@@ -95,12 +95,13 @@ export function EmptyState({
           a.leading_snug,
           a.text_center,
           a.self_center,
+          !button && a.mb_5xl,
           textStyle,
         ]}>
         {message}
       </Text>
       {button && (
-        <View style={[a.flex_shrink, a.mt_xl, a.self_center]}>
+        <View style={[a.flex_shrink, a.mt_xl, a.self_center, a.mb_5xl]}>
           <Button {...button}>
             <ButtonText>{button.text}</ButtonText>
           </Button>