fix: address PR review feedback

- Add noreferrer to rel attribute to prevent Referer header leaks
- Strip newlines from pasted text to prevent checklist corruption
- Add aria-placeholder for screen reader accessibility
- Dismiss LinkPopover on scroll/resize
- Stop keydown propagation on links in NoteCard preview

src/lib/components/Checklist.svelte

@@ -183,7 +183,7 @@
 
 	function handlePaste(e: ClipboardEvent) {
 		e.preventDefault();
-		const text = e.clipboardData?.getData('text/plain') ?? '';
+		const text = (e.clipboardData?.getData('text/plain') ?? '').replace(/[\r\n]+/g, ' ');
 		const selection = window.getSelection();
 		if (!selection?.rangeCount) return;
 		const range = selection.getRangeAt(0);
@@ -327,6 +327,7 @@
 					onblur={(e) => { (e.target as HTMLElement).innerHTML = linkifyText(item.text); }}
 					class="flex-1 min-w-0 bg-transparent text-sm outline-none break-words {item.checked ? 'text-[var(--text-muted)] line-through' : 'text-[var(--text)]'}"
 					data-placeholder="List item"
+					aria-placeholder="List item"
 					data-testid="checklist-input"
 					data-item-id={item.id}
 					role="textbox"

src/lib/components/LinkPopover.svelte

@@ -52,7 +52,7 @@
 	}
 </script>
 
-<svelte:window onclick={handleClickOutside} onkeydown={handleKeydown} />
+<svelte:window onclick={handleClickOutside} onkeydown={handleKeydown} onscroll={onClose} onresize={onClose} />
 
 <!-- svelte-ignore a11y_no_static_element_interactions -->
 <div

src/lib/components/NoteCard.svelte

@@ -134,7 +134,8 @@
 	{#if note.checklistMode && checklistItems.length > 0}
 		<!-- svelte-ignore a11y_no_noninteractive_element_interactions -->
 		<ul class="space-y-2 mb-6" data-testid="note-checklist-preview"
-			onclick={(e) => { if ((e.target as HTMLElement).closest('a')) e.stopPropagation(); }}>
+			onclick={(e) => { if ((e.target as HTMLElement).closest('a')) e.stopPropagation(); }}
+			onkeydown={(e) => { if ((e.target as HTMLElement).closest('a')) e.stopPropagation(); }}>
 			{#each sortedChecklistItems.slice(0, 8) as item}
 				<li class="flex items-start gap-2 text-sm {item.indented ? 'pl-4 ' : ''}{item.checked ? 'text-[var(--text-muted)] line-through' : 'text-[var(--text)]'}"
 					data-testid={item.indented ? 'card-checklist-child' : undefined}>