Covers the presets menu: built-ins load their rendered prompt, saved and project presets load verbatim, a row's delete deletes (via the right tier's handler) without loading, an empty project group is hidden, and "New preset…" appears only where a create panel exists.

## Before writing SPEC.md files

Read https://raw.githubusercontent.com/brillout/sdd/refs/heads/main/sdd.md
