Add public Trace demo and quickstart

[maveryn]

Summary

• add a CPU-only Hugging Face Space for exploring all 1,000 registered Trace tasks, including a one-click Random question action
• add an executable Colab quickstart pinned to the public source revision
• place live-demo and quickstart links prominently in the GitHub README and project-page hero
• add a representative Space screenshot and release-surface regression coverage
• make the installed-CLI release check resolve virtual-environment commands correctly on Windows and POSIX

Why

Trace already exposes strong generation and verification contracts, but visitors previously had to install the package and read deep into the documentation before trying it. These changes provide an immediate interactive path and a minimal reproducible notebook before the public launch.

The release-check portability fix addresses a POSIX-only assumption that virtual-environment commands always live under bin/; Windows places them under Scripts/ and uses .exe entry points.

Impact

Visitors can now generate deterministic tasks in the browser, inspect typed supervision, annotations, verifier contracts, and public traces, or run the same workflow in Colab. The Space samples uniformly across the full registered task catalog and keeps domain, scene, task, and seed selectors synchronized.

Live demo: https://huggingface.co/spaces/maveryn/trace

Validation

• 53 passed across Space, visibility, notebook, and public-release regression tests
• Ruff checks passed for the changed Python files
• git diff --check passed
• strict MkDocs build passed
• local Edge browser test passed with no console or page errors
• production Space browser test generated synchronized selectors, two images, a prompt, typed result, and verifier output
• deployed Space revision dc1de2c357d1a7bb9ee4ddb3ed11429ce0b95f0b is running on CPU Basic