feat: distinguish new notes (green dot) from modified notes (orange dot)

New notes created in-session show a green dot; existing notes with
uncommitted git changes show an orange dot. Saving a new note clears
the green dot; git commit clears the orange dot.

Introduces NoteStatus type ('new' | 'modified' | 'clean'), extracts
useNewNoteTracker hook and resolveNoteStatus pure function, and adds
onNoteSaved callback to useEditorSave for clearing new-note tracking.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/hooks/useEditorSave.ts

@@ -13,13 +13,16 @@ interface EditorSaveConfig {
   setTabs: (fn: SetStateAction<any[]>) => void
   setToastMessage: (msg: string | null) => void
   onAfterSave?: () => void
+  onNoteSaved?: (path: string) => void
 }
 
 /**
  * Hook that manages explicit save (Cmd+S) for editor content.
  * Tracks pending (unsaved) content and provides save + pre-rename helpers.
  */
-export function useEditorSave({ updateVaultContent, setTabs, setToastMessage, onAfterSave }: EditorSaveConfig) {
+const noop = () => {}
+
+export function useEditorSave({ updateVaultContent, setTabs, setToastMessage, onAfterSave = noop, onNoteSaved }: EditorSaveConfig) {
   const pendingContentRef = useRef<{ path: string; content: string } | null>(null)
 
   const updateTabAndContent = useCallback((path: string, content: string) => {
@@ -38,15 +41,16 @@ export function useEditorSave({ updateVaultContent, setTabs, setToastMessage, on
     if (pathFilter && pending.path !== pathFilter) return false
     await saveNote(pending.path, pending.content)
     pendingContentRef.current = null
+    onNoteSaved?.(pending.path)
     return true
-  }, [saveNote])
+  }, [saveNote, onNoteSaved])
 
   /** Called by Cmd+S — persists the current editor content to disk */
   const handleSave = useCallback(async () => {
     try {
       const saved = await flushPending()
       setToastMessage(saved ? 'Saved' : 'Nothing to save')
-      onAfterSave?.()
+      onAfterSave()
     } catch (err) {
       console.error('Save failed:', err)
       setToastMessage(`Save failed: ${err}`)