Adds comprehensive content transformation for Codex compatibility:
1. Task agent calls: `Task agent-name(args)` → `Use the $agent-name skill to: args`
2. Slash commands: `/command-name` → `/prompts:command-name`
3. Agent references: `@agent-name` → `$agent-name skill`
This bridges the syntax gap between Claude Code and Codex:
- Claude Code uses Task tool with subagent_types
- Codex uses skills and /prompts: namespace
Transformations are applied to both skill and prompt files during conversion.
Tested with Codex CLI 0.89.0 - all transformations working correctly.
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>