Replace Shiki code highlighting with Prism.js

web/package.json

@@ -20,11 +20,12 @@
     "gemoji": "^8.1.0",
     "katex": "^0.18.11",
     "mermaid": "^12.2.0",
-    "shiki": "^4.5.0",
+    "prismjs": "^1.30.0",
     "turndown": "^7.2.4",
     "vue": "^3.5.44"
   },
   "devDependencies": {
+    "@types/prismjs": "^1.26.6",
     "@types/turndown": "^5.0.6",
     "@vitejs/plugin-vue": "^6.0.10",
     "commonmark-spec": "^0.31.2",