chore(skills): rename all skills to domain-action convention

Adopts the whatsinagame naming pattern where the domain comes
first and the action second (e.g. pr-review, sprint-start,
audio-gen). Updated all cross-references in settings, agents,
docs, and inter-skill references.

12 renames: commit→git-commit, create-skill→skill-create,
gen-audio→audio-gen, gen-image→image-gen, plan-sprint→sprint-plan,
push-pr→pr-push, render-sprite→sprite-gen, review-pr→pr-review,
search-docs→docs-search, start-sprint→sprint-start,
start-workshop→workshop-start.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

docs/assets/visual/README.md

@@ -19,7 +19,7 @@ See [palette.md](palette.md) for art direction, "the angle", color relationships
 ## Pipeline
 
 - **3D render pipeline:** Blender model → Godot Camera3D at -72.5deg → orthographic render → outline pass → resolution downscale
-- **Render skill:** `/render-sprite` produces 12 PNGs (4 directions x 3 resolutions)
+- **Render skill:** `/sprite-gen` produces 12 PNGs (4 directions x 3 resolutions)
 - **Art direction workshop:** `docs/workshops/art-direction-mood-board/`
 
 ## Decision References