feat(create-plan/codex): switch to native superpowers workflow and add guardrails

skills/create-plan/codex/templates/milestone-plan.md

@@ -5,6 +5,12 @@
 - **Created:** YYYY-MM-DD
 - **Status:** In Progress | Complete
 
+## Planning Guardrails
+- This plan assumes design was validated before implementation planning.
+- Skills are invoked via native discovery (Codex: `~/.agents/skills/`).
+- Deprecated CLI wrappers (for example, `superpowers-codex bootstrap` / `use-skill`) are not part of this workflow.
+- Milestones require verification + local commits + explicit approval before proceeding.
+
 ## Context
 
 ### Requirements
@@ -69,17 +75,17 @@
 
 ### Types & Interfaces
 ```typescript
-// Key type definitions
+// Key type definitions (or equivalent language constructs)
 ```
 
 ### API Contracts
 ```typescript
-// Endpoint signatures, request/response shapes
+// Endpoint signatures, request/response shapes (if applicable)
 ```
 
 ### Constants & Enums
 ```typescript
-// Shared constants
+// Shared constants (if applicable)
 ```
 
 ## Files Inventory