Transform @agent- syntax to Task() calls in Codex converter

[terry-li-hm]

Summary

Fixes Codex commands that use @agent- syntax by automatically transforming them to Task() calls during conversion.

Problem

Commands like /plan_review use Claude Code's @agent-dhh-rails-reviewer syntax, which doesn't work in Codex. When these commands are converted via the Codex converter, the syntax is copied as-is, causing errors like "required review agents aren't available in this environment."

Solution

Added transformAgentSyntax() function to the Codex converter that:

• Detects @agent-<name> patterns in command bodies
• Converts them to readable text ("the dhh-rails-reviewer agent")
• Adds explicit Task() call examples with proper subagent_type
• Includes instructions for running multiple agents in parallel

Example Transformation

Before (Claude Code syntax):

Have @agent-dhh-rails-reviewer @agent-kieran-rails-reviewer review this plan in parallel.

After (Codex-compatible):

Have the dhh-rails-reviewer agent the kieran-rails-reviewer agent review this plan in parallel.

**Launch these 2 agents IN PARALLEL using the Task tool:**

Task(
  subagent_type="dhh-rails-reviewer",
  description="dhh-rails-reviewer review",
  prompt="[Your prompt here with context]"
)

Task(
  subagent_type="kieran-rails-reviewer",
  description="kieran-rails-reviewer review",
  prompt="[Your prompt here with context]"
)

**IMPORTANT:** Include all Task calls in a single message to run them in parallel.

Impact

• Fixes /plan_review and any other commands using @agent- syntax
• Maintains clean source code (plugin authors can use natural @agent- syntax)
• Automatic conversion handles the translation
• One fix benefits all current and future commands

Testing

Ran the converter and verified /plan_review now includes proper Task() call instructions in Codex format.

[terry-li-hm]

After deeper investigation, I realized this PR doesn't fully address the underlying issue.

The real problem:

• Claude Code uses Task agent-name(args) to spawn subagents
• The converter already converts agents → Codex skills (e.g., repo-research-analyst skill exists)
• But commands still contained the raw Task agent-name(...) syntax, which Codex doesn't understand
• Converting @agent-X syntax (this PR) helps with one notation, but most commands use the Task form directly

Better solution:
Transform Task agent-name(args) → Use the $agent-name skill to: args in the converter itself.

This connects the already-converted agent skills to the commands that reference them.

Closing in favor of #119 which implements this transformation in the Codex converter.

[terry-li-hm]

Correction: The new PR is #120 (not #119).

Also found and fixed an additional bug during testing - the converter was transforming the skill files but not the prompt files. Both now correctly transform Task agent(args) → Use the $agent skill to: args.

Verified locally with Codex CLI 0.89.0 - both skill and prompt files now have correct syntax.