feat: rename keep-notes to memento-note, migrate to PostgreSQL, fix MCP bugs

- Rename directory keep-notes -> memento-note with all code references
- Prisma: SQLite -> PostgreSQL (both app and MCP server schemas)
- Sync MCP schema with main app (add missing fields, relations, indexes)
- Delete 17 SQLite migrations (clean slate for PostgreSQL)
- Remove SQLite dependencies (@libsql/client, better-sqlite3, etc.)
- Fix MCP server: hardcoded Windows DB paths -> DATABASE_URL env var
- Fix MCP server: .dockerignore excluded index-sse.js (SSE mode broken)
- MCP Dockerfile: node:20 -> node:22
- Docker Compose: add postgres service, remove SQLite volume
- Generate favicon.ico, icon-192.png, icon-512.png, apple-icon.png
- Update layout.tsx icons and manifest.json for PNG icons
- Update all .env files for PostgreSQL
- Rewrite README.md with updated sections
- Remove mcp-server/node_modules and prisma/client-generated from git tracking

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

memento-note/context/notebook-drag-context.tsx

@@ -0,0 +1,64 @@
+'use client'
+
+import { createContext, useContext, useState, useCallback, ReactNode } from 'react'
+
+interface NotebookDragContextValue {
+  draggedNoteId: string | null
+  dragOverNotebookId: string | null
+  startDrag: (noteId: string) => void
+  endDrag: () => void
+  dragOver: (notebookId: string | null) => void
+  isDragging: boolean
+  isDragOver: boolean
+}
+
+const NotebookDragContext = createContext<NotebookDragContextValue | null>(null)
+
+export function useNotebookDrag() {
+  const context = useContext(NotebookDragContext)
+  if (!context) {
+    throw new Error('useNotebookDrag must be used within NotebookDragProvider')
+  }
+  return context
+}
+
+interface NotebookDragProviderProps {
+  children: ReactNode
+}
+
+export function NotebookDragProvider({ children }: NotebookDragProviderProps) {
+  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 (
+    <NotebookDragContext.Provider
+      value={{
+        draggedNoteId,
+        dragOverNotebookId,
+        startDrag,
+        endDrag,
+        dragOver,
+        isDragging,
+        isDragOver,
+      }}
+    >
+      {children}
+    </NotebookDragContext.Provider>
+  )
+}