debug: add logging to diagnose bookmark grouping issue

Added console logs in groupIndividualBookmarks to show:
- Distribution of sourceKind values across all bookmarks
- Sample items with their sourceKind, isPrivate, setName, and id
- Count of items in each group after filtering

This will help identify why grouped view shows only ~40 bookmarks
while flat view shows 500+.

src/utils/bookmarkUtils.tsx

@@ -93,6 +93,23 @@ export const sortIndividualBookmarks = (items: IndividualBookmark[]) => {
 export function groupIndividualBookmarks(items: IndividualBookmark[]) {
   const sorted = sortIndividualBookmarks(items)
   
+  // Debug: log what sourceKind values we're seeing
+  const sourceKindCounts = new Map<number | undefined, number>()
+  sorted.forEach(i => {
+    const count = sourceKindCounts.get(i.sourceKind) || 0
+    sourceKindCounts.set(i.sourceKind, count + 1)
+  })
+  console.log('[bookmark] 📊 SourceKind distribution:', Object.fromEntries(sourceKindCounts))
+  
+  // Sample a few items to see their properties
+  const samples = sorted.slice(0, 5).map(i => ({
+    sourceKind: i.sourceKind,
+    isPrivate: i.isPrivate,
+    setName: i.setName,
+    id: i.id.slice(0, 20)
+  }))
+  console.log('[bookmark] 📊 Sample items:', samples)
+  
   // Group by source list, not by content type
   const nip51Public = sorted.filter(i => i.sourceKind === 10003 && !i.isPrivate)
   const nip51Private = sorted.filter(i => i.sourceKind === 10003 && i.isPrivate)
@@ -101,6 +118,15 @@ export function groupIndividualBookmarks(items: IndividualBookmark[]) {
   const amethystPrivate = sorted.filter(i => i.sourceKind === 30001 && i.isPrivate && i.setName === 'bookmark')
   const standaloneWeb = sorted.filter(i => i.sourceKind === 39701)
   
+  console.log('[bookmark] 📊 After grouping:', {
+    nip51Public: nip51Public.length,
+    nip51Private: nip51Private.length,
+    amethystPublic: amethystPublic.length,
+    amethystPrivate: amethystPrivate.length,
+    standaloneWeb: standaloneWeb.length,
+    total: sorted.length
+  })
+  
   return { 
     nip51Public, 
     nip51Private,