chore: clean up repo for public release

- Remove BMAD framework, IDE configs, dev screenshots, test files,
  internal docs, and backup files
- Rename keep-notes/ to memento-note/
- Update all references from keep-notes to memento-note
- Add Apache 2.0 license with Commons Clause (non-commercial restriction)
- Add clean .gitignore and .env.docker.example

memento-note/hooks/use-note-drag.ts

@@ -0,0 +1,36 @@
+'use client'
+
+import { useState, useCallback } from 'react'
+
+export type DragState = 'idle' | 'dragging' | 'drag-over'
+
+export function useNoteDrag() {
+  const [draggedNoteId, setDraggedNoteId] = useState<string | null>(null)
+  const [dragOverNotebookId, setDragOverNotebookId] = useState<string | null>(null)
+
+  const startDrag = useCallback((noteId: string) => {
+    setDraggedNoteId(noteId)
+  }, [])
+
+  const endDrag = useCallback(() => {
+    setDraggedNoteId(null)
+    setDragOverNotebookId(null)
+  }, [])
+
+  const dragOver = useCallback((notebookId: string | null) => {
+    setDragOverNotebookId(notebookId)
+  }, [])
+
+  const isDragging = draggedNoteId !== null
+  const isDragOver = dragOverNotebookId !== null
+
+  return {
+    draggedNoteId,
+    dragOverNotebookId,
+    startDrag,
+    endDrag,
+    dragOver,
+    isDragging,
+    isDragOver,
+  }
+}