Fix Codex skill version metadata (#703)

Move Codex and .agents skill versions under metadata while keeping all version readers compatible with legacy top-level frontmatter.\n\nAI assistance: prepared with Codex under maintainer direction.

scripts/lib/transformers/factory.js

@@ -241,6 +241,7 @@ export function createTransformer(config) {
     providerTags = [provider],
     writeOpenAIMetadata = false,
     includeVersion = true,
+    versionInMetadata = false,
   } = config;
   const placeholderKey = placeholderProvider || provider;
 
@@ -274,7 +275,9 @@ export function createTransformer(config) {
         name: skillName,
         description: skill.description,
       };
-      if (skillsVersion && includeVersion) frontmatterObj.version = skillsVersion;
+      if (skillsVersion && includeVersion && !versionInMetadata) {
+        frontmatterObj.version = skillsVersion;
+      }
 
       for (const spec of activeFields) {
         if (spec.condition && !spec.condition(skill)) continue;
@@ -282,6 +285,13 @@ export function createTransformer(config) {
         if (val) frontmatterObj[spec.yamlKey] = val;
       }
 
+      if (skillsVersion && includeVersion && versionInMetadata) {
+        frontmatterObj.metadata = {
+          ...(frontmatterObj.metadata || {}),
+          version: skillsVersion,
+        };
+      }
+
       // Replace {{command_hint}} in argument-hint with command names from metadata,
       // grouped by category with middle dots between groups for natural line-breaking.
       if (frontmatterObj['argument-hint']?.includes('{{command_hint}}')) {