new-referencelisted

# New reference Create a new primary reference file from scratch and wire it into the navigator's catalog. Use this when a single topic has been identified ahead of time and a full discover pass would be overkill. The proposal stages (into `$CTX_PROPOSED/`, never the live tree): - A new file under `references/<source-slug>-<topic>.md` (the reference itself) — manifest status `added`. - A new row in the navigator's catalog table at `SKILL.md` pointing at that reference — manifest status `modified` (the live `SKILL.md` is copied into `$CTX_PROPOSED/` copy-on-write, then the row is added there). It does NOT write to `research/.research-state.json` — that file is a binary setup marker only. If the new reference covers a topic from an as-yet-unregistered source, the source is added to `research/source-paths.json` (status `modified`, same copy-on-write seed) as part of the same proposal. Every other file in the contextualizer is recorded `unchanged`. The whole proposal lands live only when the user runs `/skill-engine:apply <name>`. For `kind: git-managed` sources, the proposed entry follows the same omit-on-default convention as `engine-bootstrap` Step 2.4: `branch` is recorded only when the contextualizer follows a non-default branch (`dev`, `nonprod`, `release/v2`); absent ⇒ HEAD. NEW does not prompt for a branch at registration time — the maintainer can supply `"branch": "<name>"` in the proposed entry directly during the approval gesture, or edit `source-paths.json`