feat: landing page UI, fix inference crash on 401, all scores clamped

fix: clamp all scores strictly (0,1), no 400s, no env crashes

fix: clamp all scores strictly (0,1) for task validation

fix: add uv.lock, main() entry point, openenv-core dependency

fix: version bump to 0.4.0, add citation_verification task

Replace with ScholarEnv v0.4.0 - complete rewrite

updated folder structure and added uv