Always run build on first install

So builds/application.js is not missing.

Author: dhh

lib/install/esbuild/install.rb

@@ -8,4 +8,5 @@
   say %(Add "scripts": { "build": "#{build_script}" } to your package.json), :green
 else
   run %(npm set-script build "#{build_script}")
+  run %(yarn build)
 end

lib/install/rollup/install.rb

@@ -9,4 +9,5 @@
   say %(Add "scripts": { "build": "#{build_script}" } to your package.json), :green
 else
   run %(npm set-script build "#{build_script}")
+  run %(yarn build)
 end

lib/install/webpack/install.rb

@@ -9,4 +9,5 @@
   say %(Add "scripts": { "build": "#{build_script}" } to your package.json), :green
 else
   run %(npm set-script build "#{build_script}")
+  run %(yarn build)
 end