add tsc build step and publish packages as @hatk/hatk and @hatk/oauth-client
Switches hatk from shipping raw TypeScript to compiled JS via tsc.
Renames npm package from hatk to @hatk/hatk (npm blocked the unscoped name).
Updates all codegen templates and path references for the new package name.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>