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/app/(main)/page.tsx

@@ -152,23 +152,20 @@ export default function HomePage() {
   // Enable reminder notifications
   useReminderCheck(notes)
 
-  // Load user settings to check if recent notes should be shown
+  // Load settings + notes in a single effect to avoid cascade re-renders
   useEffect(() => {
-    const loadSettings = async () => {
+    const load = async () => {
+      // Load settings first
+      let showRecent = true
       try {
         const settings = await getAISettings()
-        // Default to true if setting is undefined or null
-        setShowRecentNotes(settings?.showRecentNotes !== false)
+        showRecent = settings?.showRecentNotes !== false
       } catch (error) {
         // Default to true on error
-        setShowRecentNotes(true)
       }
-    }
-    loadSettings()
-  }, [refreshKey])
+      setShowRecentNotes(showRecent)
 
-  useEffect(() => {
-    const loadNotes = async () => {
+      // Then load notes
       setIsLoading(true)
       const search = searchParams.get('search')?.trim() || null
       const semanticMode = searchParams.get('semantic') === 'true'
@@ -214,7 +211,7 @@ export default function HomePage() {
       setPinnedNotes(pinnedFilter)
 
       // Derive recent notes from already-fetched allNotes (no extra server call)
-      if (showRecentNotes) {
+      if (showRecent) {
         const sevenDaysAgo = new Date()
         sevenDaysAgo.setDate(sevenDaysAgo.getDate() - 7)
         sevenDaysAgo.setHours(0, 0, 0, 0)
@@ -240,9 +237,9 @@ export default function HomePage() {
       setIsLoading(false)
     }
 
-    loadNotes()
+    load()
     // eslint-disable-next-line react-hooks/exhaustive-deps
-  }, [searchParams, refreshKey, showRecentNotes]) // Intentionally omit 'labels' and 'semantic' to prevent reload when adding tags or from router.push
+  }, [searchParams, refreshKey]) // Intentionally omit 'labels' to prevent reload when adding tags
   // Get notebooks context to display header
   const { notebooks } = useNotebooks()
   const currentNotebook = notebooks.find((n: any) => n.id === searchParams.get('notebook'))