feat: use tsnapi for exports snapshoting

tsdown.config.ts

@@ -1,4 +1,6 @@
+import process from 'node:process'
 import { defineConfig } from 'tsdown'
+import ApiSnapshot from 'tsnapi/rolldown'
 
 export default defineConfig({
   entry: [
@@ -7,4 +9,10 @@ export default defineConfig({
   dts: true,
   exports: true,
   publint: true,
+  plugins: [
+    ApiSnapshot({
+      // TODO: remove this when the library is stable to guard against breaking changes
+      update: !process.env.CI,
+    }),
+  ],
 })