perf: eliminate N+1 getNoteAllUsers calls and merge loadSettings+loadNotes to fix double-render cascade

- Skip getNoteAllUsers server action for for own notes (majority of notes), Only fetch collaborators for shared notes.
- Merge loadSettings and loadNotes into single useEffect to prevent double loadNotes trigger when showRecentNotes state changes.

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

keep-notes/components/note-card.tsx

@@ -184,17 +184,30 @@ export const NoteCard = memo(function NoteCard({
   const isSharedNote = currentUserId && note.userId && currentUserId !== note.userId
   const isOwner = currentUserId && note.userId && currentUserId === note.userId
 
-  // Load collaborators when note changes
+  // Load collaborators only for shared notes (not owned by current user)
   useEffect(() => {
+    // Skip API call for notes owned by current user — no need to fetch collaborators
+    if (!isSharedNote) {
+      // For own notes, set owner to current user
+      if (currentUserId && session?.user) {
+        setOwner({
+          id: currentUserId,
+          name: session.user.name,
+          email: session.user.email,
+          image: session.user.image,
+        })
+      }
+      return
+    }
+
     let isMounted = true
-    
+
     const loadCollaborators = async () => {
       if (note.userId && isMounted) {
         try {
           const users = await getNoteAllUsers(note.id)
           if (isMounted) {
             setCollaborators(users)
-            // Owner is always first in the list
             if (users.length > 0) {
               setOwner(users[0])
             }
@@ -209,11 +222,11 @@ export const NoteCard = memo(function NoteCard({
     }
 
     loadCollaborators()
-    
+
     return () => {
       isMounted = false
     }
-  }, [note.id, note.userId])
+  }, [note.id, note.userId, isSharedNote, currentUserId, session?.user])
 
   const handleDelete = async () => {
     if (confirm(t('notes.confirmDelete'))) {