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/providers.js

@@ -48,6 +48,9 @@ export const PROVIDERS = {
     configDir: '.codex',
     displayName: 'Codex',
     frontmatterFields: [],
+    // Codex's validator rejects unknown top-level keys. Version remains
+    // available to Impeccable's updater under the spec-defined metadata map.
+    versionInMetadata: true,
     writeOpenAIMetadata: true,
     // No agentFormat: the Codex subagent ships nested inside the skill's own
     // agents/ folder (see CODEX_SKILL_PROVIDERS in factory.js), which Codex
@@ -63,6 +66,7 @@ export const PROVIDERS = {
     displayName: 'Codex Repo Skills',
     placeholderProvider: 'codex',
     frontmatterFields: [],
+    versionInMetadata: true,
     writeOpenAIMetadata: true,
   },
   github: {