fix(mcp-server): make edit_diagram all-or-nothing and fix preview sync races

- edit_diagram applies nothing when any operation fails, rejects invalid or
  multi-cell new_xml, validates only the target page, and returns the
  current page XML on every rejection (including stale edits)
- Fix get_diagram reading the old diagram right after an AI write: the
  preview pushed its sync reply with a newer version than it was taken at
- Keep a user edit that loses the race with an AI write in history and
  tell the user in the preview
- Autofix removes only exact foreign tags (a stray <mxGraph/> deleted
  <mxGraphModel>), fixes tag case, drops orphan <mxPoint>s, and rejects
  unknown element names in model XML
- Edit empty and compressed pages; PNG exports use the page on screen;
  tag download exports; reload from the server after a page export
- Expand ~ in paths, tell the model when the browser sync timed out,
  use registerPrompt, require SDK ^1.31.0

packages/mcp-server/package.json

@@ -1,6 +1,6 @@
 {
     "name": "@next-ai-drawio/mcp-server",
-    "version": "0.2.3",
+    "version": "0.2.4",
     "description": "MCP server for Next AI Draw.io - AI-powered diagram generation with real-time browser preview",
     "type": "module",
     "main": "dist/index.js",
@@ -38,7 +38,7 @@
         "access": "public"
     },
     "dependencies": {
-        "@modelcontextprotocol/sdk": "^1.0.4",
+        "@modelcontextprotocol/sdk": "^1.31.0",
         "linkedom": "^0.18.0",
         "open": "^11.0.0",
         "saxes": "^6.0.0",