Add loose: false to SWC config for Stimulus compatibility

Override Shakapacker's default loose: true setting with loose: false
to ensure spec-compliant class transforms that work with Stimulus.

Without this, Stimulus controllers fail silently even with
keepClassNames: true.

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

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

Author: justin808

config/swc.config.js

@@ -5,6 +5,9 @@ const customConfig = {
     jsc: {
       // Preserve class names for Stimulus controller discovery
       keepClassNames: true,
+      // Use spec-compliant transforms (override Shakapacker's loose: true default)
+      // This is required for Stimulus controllers to work correctly
+      loose: false,
       transform: {
         react: {
           // Use automatic runtime (React 17+) - no need to import React