feat: Individual page export in Markdown and HTML formats (#80)

* fix maths node

* render default html width

* Add page export module
* with support for html and markdown exports

* Page export UI
* Add PDF print too

* remove unused import

apps/client/package.json

@@ -26,6 +26,7 @@
     "clsx": "^2.1.1",
     "date-fns": "^3.6.0",
     "emoji-mart": "^5.6.0",
+    "file-saver": "^2.0.5",
     "jotai": "^2.8.3",
     "jotai-optics": "^0.4.0",
     "js-cookie": "^3.0.5",