Add tracked AI skills for Blender assets and release QA

TODO.md

@@ -618,6 +618,17 @@ three-up boards; `tools/refboard.py` + reference-anchored generation (`--referen
 - [ ] Prefer `tools/scene_concepts.py promote` (or a manual move into `game_ready/v2/` plus a
       `PICKS` entry) so new picks follow the same path as `limestone_ashlar` and `dark_stucco`.
 
+### Agent skill upkeep
+
+- [x] Add the tracked project skills `gig-line-blender-asset-contract` and
+      `gig-line-release-qa` under `.agents/skills/`, with references for the
+      asset contract/verification and release/QA runbooks.
+- [x] Keep the third-party `blender-skills` pack local/gitignored while allowing
+      project-authored skills to be committed; reference the skills from
+      `tools/README.md`, `AGENTS.md` and `MEMORY.md`.
+- [ ] Revisit the skills after the next Blender or release work changes the
+      contract, commands or gates; stale skills are worse than no skill.
+
 ### Blender skills upkeep
 
 - [ ] Re-check the installed Blender pack (`version.json`) when updating it and record the version