Add Linux distribution and WSL2 validation for base-cli

[codeforester]

Parent: #35

Goal

Validate the Linux and WSL2 support tiers against representative environments.

Scope

• Add CI coverage for the current Ubuntu runner plus representative Debian and Fedora/RHEL-family environments.
• Exercise the supported Python floor and a current Python release.
• Add package install and runtime smoke checks, not just import checks.
• Add a documented WSL2 smoke procedure that runs inside the Linux distribution.
• Explicitly test/document the supported Linux filesystem path and the limitations of Windows-mounted WSL paths.
• Keep distro package-manager setup outside the library's contract.

Acceptance criteria

• CI demonstrates the same base-cli behavior across Ubuntu/Debian and Fedora/RHEL-family environments.
• WSL2 validation is repeatable by a maintainer, even if it is manual or workflow-dispatch-only initially.
• Failures identify platform assumptions rather than producing opaque errors.