docs: note Claude for Open Source program support in README

Author: iamtoruk

README.md

@@ -13,6 +13,8 @@
     <a href="https://github.com/sponsors/iamtoruk"><img src="https://img.shields.io/badge/sponsor-♥-ea4aaa?logo=github" alt="Sponsor" /></a>                                                  
   </p> 
 
+<p align="center"><sub>Maintained with support from Anthropic's Claude for Open Source program.</sub></p>
+
 CodeBurn tracks token usage, cost, and performance across **25 AI agents**. It breaks down spending by task type, model, tool, project, and provider so you can see exactly where your budget goes.
 
 Everything runs locally. No wrapper, no proxy, no API keys. CodeBurn reads session data directly from disk and prices every call using [LiteLLM](https://github.com/BerriAI/litellm).