feat: identidy jan for openrouter

[STRRL]

Describe Your Changes

• update header template for openrouter, add HTTP-Referer: https://jan.ai, X-Title: Jan

reference: https://openrouter.ai/docs/api-reference/overview#headers

Fixes Issues

• Closes #5388

Self Checklist

• [x] Added relevant comments, esp in complex areas
• [ ] Updated docs (for bug fixes / features)
• [ ] Created issues for follow-up changes or refactoring needed

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[!IMPORTANT] Update header_template in openrouter.json to include HTTP-Referer and X-Title headers for OpenRouter API requests.

• Behavior:
  • Update header_template in openrouter.json to include HTTP-Referer: https://jan.ai and X-Title: Jan for OpenRouter API requests.
• References:
  • Closes issue #5388.
  • Based on OpenRouter API documentation.

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