Fix knip configuration for pnpm migration

- Remove @babel/runtime and mini-css-extract-plugin from ignoreDependencies
  (now properly detected by knip with pnpm)
- Restore missing ignoreDependencies for dummy app React components
- Keep disableHttp2 export ignore for test utilities

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: justin808

knip.ts

@@ -177,10 +177,6 @@ const config: KnipConfig = {
         '@rescript/react',
         // The Babel plugin fails to detect it
         'babel-plugin-transform-react-remove-prop-types',
-        // Required by @babel/plugin-transform-runtime for polyfills
-        '@babel/runtime',
-        // Used in webpack server config to filter out MiniCssExtractPlugin
-        'mini-css-extract-plugin',
         // This one is weird. It's long-deprecated and shouldn't be necessary.
         // Probably need to update the Webpack config.
         'node-libs-browser',
@@ -193,6 +189,14 @@ const config: KnipConfig = {
         'sass-resources-loader',
         'style-loader',
         'url-loader',
+        // Used in ignored client/app components (dynamically loaded by React on Rails)
+        'create-react-class',
+        'react-helmet',
+        '@types/react-helmet',
+        'react-redux',
+        'react-router-dom',
+        // Transitive dependency of shakapacker but listed as direct dependency
+        'webpack-merge',
       ],
     },
   },