Preview and apply a plugin

Dry-run a catalog plugin against a project, then apply it and confirm the result.

Tape: ../tapes/07-preview-apply-plugin.tape (CLI repo tape)

Commands

1. ht init --harnesses codex,claude-code,cursor: initialise HarnessTap and set harness preferences
2. ht plugin list --search foundation --remote-only: browse catalog plugins
3. ht apply engineering-foundation --dry-run: preview planned writes
4. ht apply engineering-foundation: materialize the plugin into the project
5. ht status .: confirm the final state