add types to package.json

I'm surprised this is needed, but it seems to be. Types are not being inferred with just the `exports.types` field. This seems to be the case on npmjs.com, in VSCode, and via the typescript compiler.

package.json

@@ -15,6 +15,7 @@
 		"types": "./build/index.d.ts",
 		"default": "./build/index.js"
 	},
+	"types": "./build/index.d.ts",
 	"sideEffects": false,
 	"engines": {
 		"node": ">=18"