Add PDF modal and selectedPost setter

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

package.json

@@ -2,6 +2,7 @@
   "name": "endorsement-frontend",
   "version": "0.1.0",
   "private": true,
+  "type": "module",
   "scripts": {
     "dev": "vite",
     "build": "vite build",
@@ -12,7 +13,7 @@
     "react": "^19.0.0",
     "react-dom": "^19.0.0",
     "react-router-dom": "^6.14.1",
-    "zustand": "^4.5.9"
+    "zustand": "^4"
   },
   "devDependencies": {
     "typescript": "^5.5.0",