refactor: use Tailwind CLI and esbuild for assets

Fixes: #10
Fixes: #14

esbuild.config.js

@@ -0,0 +1,28 @@
+const esbuild = require('esbuild')
+
+let minify = false
+let sourcemap = true
+let watch_fs = true
+
+if (process.env.NODE_ENV === 'production') {
+  minify = true
+  sourcemap = false
+  watch_fs = false
+}
+
+const watch = watch_fs && {
+  onRebuild(error) {
+    if (error) console.error('[watch] build failed', error)
+    else console.log('[watch] build finished')
+  },
+}
+
+esbuild.build({
+  entryPoints: ['./assets/js/app.js'],
+  outfile: './build/app.js',
+  bundle: true,
+  minify: minify,
+  sourcemap: sourcemap,
+  watch: watch,
+  plugins: [],
+})