Update SmolVM to latest version 0.0.28

[nueces]

Changes:

• Updated SmolVM:

  • pyproject.toml: smolvm==0.0.28
  • uv.lock refreshed

• Suppressed SmolVM update notices by default:

  • src/sbx/runtime.py
  • added env_boolean(...)
  • added smolvm_env(...)
  • defaults SMOLVM_DISABLE_VERSION_CHECK=1
  • opt-in via SBX_SMOLVM_VERSION_NOTICES=true

• Wired SmolVM env into CLI/runtime calls:

  • src/sbx/cli.py
  • src/sbx/runtime.py

• Added VM clock sync after boot:

  • src/sbx/cli.py
  • sets guest UTC time from host
  • sets guest timezone from host /etc/localtime or /etc/timezone

• Increased default boot timeout:

  • src/sbx/constants.py
  • 30s → 60s
  • CLI help updated

• Tests updated/added:

  • tests/test_runtime.py added
  • tests/test_cli.py updated
  • tests/test_cli_extra.py updated

Validated:

  ruff check src tests: passed
  pytest --no-cov: 182 passed