Fix race condition: build ReScript before starting webpack

Added 'yarn res:build' to wp-client and wp-server commands in Procfile.dev
to ensure ReScript files are compiled before webpack tries to bundle them.

This prevents webpack module resolution errors on first startup when the
.bs.js files don't exist yet.

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

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

Author: justin808

Procfile.dev

@@ -3,5 +3,5 @@
 rescript: yarn res:dev
 redis: redis-server
 rails: bundle exec rails s -p 3000
-wp-client: HMR=true RAILS_ENV=development NODE_ENV=development bin/shakapacker-dev-server
-wp-server: bundle exec rake react_on_rails:locale && HMR=true SERVER_BUNDLE_ONLY=yes bin/shakapacker --watch
+wp-client: yarn res:build && HMR=true RAILS_ENV=development NODE_ENV=development bin/shakapacker-dev-server
+wp-server: yarn res:build && bundle exec rake react_on_rails:locale && HMR=true SERVER_BUNDLE_ONLY=yes bin/shakapacker --watch