Fix CBT history react-markdown crash, fix test deletion cascade, fix cbt theme, add 180 NEET questions

package-lock.json

@@ -17,6 +17,7 @@
         "katex": "^0.17.0",
         "lucide-react": "^1.21.0",
         "next": "16.2.9",
+        "next-themes": "^0.4.6",
         "react": "19.2.4",
         "react-datepicker": "^9.1.0",
         "react-dom": "19.2.4",
@@ -27,6 +28,7 @@
         "rehype-raw": "^7.0.0",
         "remark-math": "^6.0.0",
         "tailwind-merge": "^3.6.0",
+        "zod": "^4.4.3",
         "zustand": "^5.0.14"
       },
       "devDependencies": {
@@ -6754,6 +6756,16 @@
         }
       }
     },
+    "node_modules/next-themes": {
+      "version": "0.4.6",
+      "resolved": "https://registry.npmjs.org/next-themes/-/next-themes-0.4.6.tgz",
+      "integrity": "sha512-pZvgD5L0IEvX5/9GWyHMf3m8BKiVQwsCMHfoFosXtXBMnaS0ZnIJ9ST4b4NqLVKDEm8QBxoNNGNaBv2JNF6XNA==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": "^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc",
+        "react-dom": "^16.8 || ^17 || ^18 || ^19 || ^19.0.0-rc"
+      }
+    },
     "node_modules/next/node_modules/postcss": {
       "version": "8.4.31",
       "resolved": "https://registry.npmjs.org/postcss/-/postcss-8.4.31.tgz",
@@ -8888,7 +8900,6 @@
       "version": "4.4.3",
       "resolved": "https://registry.npmjs.org/zod/-/zod-4.4.3.tgz",
       "integrity": "sha512-ytENFjIJFl2UwYglde2jchW2Hwm4GJFLDiSXWdTrJQBIN9Fcyp7n4DhxJEiWNAJMV1/BqWfW/kkg71UDcHJyTQ==",
-      "dev": true,
       "license": "MIT",
       "funding": {
         "url": "https://github.com/sponsors/colinhacks"