v0.2.4

:zap: Zsh: dual-array _describe + _message protocol

- Print Zsh output as three-field tab-delimited (value\\tdisplay\\tdescription)
- Rewrite zsh.zsh with dual-array _describe — value no longer needs : escaping
- Route UI logs through __msg__ protocol + _message instead of fake items
- Remove dummy placeholder item for Zsh

:adhesive_bandage: Fix upgrade version comparison (semver, prevent downgrade)
:adhesive_bandage: Fix Linux asset name: gnu -> musl (match GitHub workflow)