fix: improve markdown detection and fix line spacing in embedded notes

Count total occurrences of medium signals in containsMarkdown instead of
only distinct types, so repeated patterns like multiple list items
correctly trigger markdown rendering. Add whitespace-normal to
MarkdownContent to prevent inherited whitespace-pre-wrap from parent
note content causing inconsistent line spacing in embedded notes.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/MarkdownContent/index.tsx

@@ -122,7 +122,7 @@ export default function MarkdownContent({
   )
 
   return (
-    <div className="space-y-3">
+    <div className="space-y-3 whitespace-normal">
       <Markdown
         remarkPlugins={[remarkGfm, remarkNostr, remarkInlineContent]}
         urlTransform={(url) => {

src/lib/markdown.ts

@@ -34,10 +34,10 @@ export function containsMarkdown(content: string): boolean {
 
   let matchCount = 0
   for (const pattern of mediumPatterns) {
-    if (pattern.test(cleaned)) {
-      matchCount++
-      if (matchCount >= 2) return true
-    }
+    const globalPattern = new RegExp(pattern.source, pattern.flags.includes('m') ? 'gm' : 'g')
+    const occurrences = (cleaned.match(globalPattern) || []).length
+    matchCount += occurrences
+    if (matchCount >= 2) return true
   }
 
   return false