fix: replace read-only useClipboard ref with writable shallowRef

copiedReadme from useClipboard's copied is a read-only computed —
direct assignment fails type checking. Since we now bypass
useClipboard's copy() entirely, replace with a writable shallowRef.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: howwohmm

app/pages/package/[[org]]/[name].vue

@@ -96,10 +96,7 @@ const {
 )
 
 //copy README file as Markdown
-const { copied: copiedReadme, copy: copyReadme } = useClipboard({
-  source: () => '',
-  copiedDuring: 2000,
-})
+const copiedReadme = shallowRef(false)
 
 function prefetchReadmeMarkdown() {
   if (readmeMarkdownStatus.value === 'idle') {