feat: add typescript declaration files

Types are automatically generated from the existsing
JSDoc comments in the js source code. Use `types:build`
script from `package.json` to produce d.ts files.

types/index.d.ts

@@ -0,0 +1,2 @@
+export { pingJava } from "./lib/java.js";
+export { pingBedrock } from "./lib/bedrock.js";