Add semantic-tag release workflow for zunit binaries

[ss-o]

Context

The workspace now distinguishes continuous-deploy repositories from semantic-tag release repositories. zunit belongs to the semantic-tag class and should not mint a user-facing release merely because next was merged into main.

Scope

• confirm the intended release artifact(s)
• define the release trigger (v*.*.* semantic tag)
• add or update CI only after the release contract is clear
• keep main as continuous validation only

Suggested tracker fields

• Item type: Task
• Priority: Medium
• Effort: Medium
• Status: Backlog