chore: pin playwright mcp and drop unused MDX TS plugin

- Pin @playwright/mcp to 0.0.78 instead of @latest for a deterministic,
  supply-chain-safer MCP server version.
- Remove the @mdx-js/typescript-plugin devDependency and tsconfig plugin
  entry; the workshop is pure Markdown with no .mdx files (Starlight's own
  MDX support remains transitive and untouched).
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 64357866-3a3f-4fd8-914b-77826de5be5a

Author: GeekTrainer

.mcp.json

@@ -3,7 +3,7 @@
     "playwright": {
       "type": "stdio",
       "command": "npx",
-      "args": ["-y", "@playwright/mcp@latest"],
+      "args": ["-y", "@playwright/mcp@0.0.78"],
       "tools": ["*"]
     }
   }

website/package-lock.json

@@ -19,7 +19,6 @@
     "typescript": "^5.7.0"
   },
   "devDependencies": {
-    "@mdx-js/typescript-plugin": "^0.1.3",
     "remark-github-admonitions-to-directives": "^2.1.0"
   }
 }

website/package.json

@@ -6,9 +6,6 @@
     "allowArbitraryExtensions": true,
     "paths": {
       "@components/*": ["./src/components/*"]
-    },
-    "plugins": [
-      { "name": "@mdx-js/typescript-plugin" }
-    ]
+    }
   }
 }