fix(hyperlight-codeact): pin version >=0.3.0 and handle Python 3.14+

[jsturtevant]

Problem

When using the hyperlight-codeact skill, three issues prevent it from working first-try:

1. Stub package resolution — uv run --with 'hyperlight-sandbox[wasm,python_guest]' resolves to v0.0.1, which is an empty stub with no Sandbox class. The import fails with ImportError: cannot import name 'Sandbox'.

2. Python 3.14+ ABI mismatch — The hyperlight-sandbox-backend-wasm package only ships wheels for Python ≤3.13. On Python 3.14+ (now the default on many systems), uv fails to find a compatible wheel.

3. Unhelpful fallback — The _try_install function tries interactive pip/uv installs, which don't help in uv run ephemeral environments and give no indication of what actually went wrong.

Fix

scripts/codeact.py

• Add _check_python_version() — early-exits with a clear message and the exact uv run --python 3.13 command to use
• Add _import_sandbox() — detects stub packages (installed but no Sandbox attr) with an actionable error, then falls back to interactive install with the pinned version
• Pin >= in the install prompt so the stub package is never installed

SKILL.md

• Pin >=0.3.0 in all uv run --with examples
• Add --python 3.13 to all execution examples
• Update prerequisites to document Python 3.10–3.13 requirement
• Add tip about using uv run --python 3.13 on newer systems