Stop tagging unic-archon-dlc releases on main #684

Why

unic-archon-dlc is deprecated and withdrawn from the catalogue (#677, #679). The maintainer told the projects that use it that 0.29.0 is the last version. On develop its plugin.json reads 0.36.1, so the next develop → main release would create the tag unic-archon-dlc@0.36.1. A reader would take that tag as a new release of a deprecated plugin.

Acceptance criteria

1. .github/workflows/release.yml no longer calls tag_if_changed for apps/claude-code/unic-archon-dlc. Every other plugin's line is unchanged.
2. Nothing else changes: ci.yml still tests the plugin when it changes, and no file under apps/claude-code/unic-archon-dlc/ changes.
3. The tag unic-archon-dlc@0.29.0 is untouched.
4. The pull request targets develop. It lands before the next develop → main release.