implement six-skill gstack 2 runtime

plan-tune/SKILL.md

@@ -1,5 +1,5 @@
 ---
-name: plan-tune
+name: gstack-1-plan-tune
 preamble-tier: 2
 version: 1.0.0
 description: "Self-tuning question sensitivity + developer psychographic for gstack (v1: observational). (gstack)"
@@ -19,6 +19,8 @@ allowed-tools:
   - AskUserQuestion
   - Glob
   - Grep
+metadata:
+  internal: true
 ---
 <!-- AUTO-GENERATED from SKILL.md.tmpl — do not edit directly -->
 <!-- Regenerate: bun run gen:skill-docs -->