chore: scaffold carousel package and tooling

tsup.config.ts

@@ -0,0 +1,10 @@
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  entry: ['src/index.ts', 'src/dots.ts', 'src/autoplay.ts'],
+  format: 'esm',
+  dts: true,
+  clean: true,
+  // unminified on purpose — consumer bundlers minify. size-limit measures the
+  // minified+gzipped size for budgeting.
+});