Add OpenRouter app attribution headers, bump to 1.2.3

[pallaoro]

Summary

• Send HTTP-Referer: https://clawnify.com and X-OpenRouter-Title: Clawnify headers on AI step inference calls routed through OpenRouter, so usage shows up on Clawnify's app page in OpenRouter rankings.
• Headers are only attached when the OpenAI-compatible client targets OpenRouter — direct OpenAI calls are unchanged.
• Bumps version to 1.2.3.

Test plan

• CI green