chore(skills): rename gv-brainstorming to brainstorming

skills/.gitignore

@@ -14,7 +14,7 @@
 !/create-docs/
 !/format-report-fix/
 !/frontend-mobile-rules/
-!/gv-brainstorming/
+!/brainstorming/
 !/refactor-rename/
 !/review-fix-loop/
 !/session-handoff/

skills/gv-brainstorming/SKILL.md → skills/brainstorming/SKILL.md

@@ -1,5 +1,5 @@
 ---
-name: gv-brainstorming
+name: brainstorming
 description: "Orchestrates brainstorming, inspection, planning, delegated implementation, and review."
 compatibility: "Pi Coding Agent; delegated roles must be configured separately."
 ---