Fix Babel loader inputSourceMap error

Set inputSourceMap: false to prevent Babel from trying to process
webpack's source maps, which was causing the build to fail.

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

Co-Authored-By: Claude <noreply@anthropic.com>

Author: justin808

config/webpack/commonWebpackConfig.js

@@ -76,6 +76,7 @@ const stimulusRule = {
   use: {
     loader: 'babel-loader',
     options: {
+      inputSourceMap: false,
       presets: [
         ['@babel/preset-env', {
           useBuiltIns: 'entry',