fix: Add branch parameter to CI badge to force refresh

- GitHub caches badge images which can show stale status
- Adding branch=main parameter helps with cache invalidation
- CI is actually passing but badge shows red due to caching

Author: raold

README.md

@@ -5,7 +5,7 @@
 [![Python](https://img.shields.io/badge/python-3.11+-blue.svg)](https://www.python.org/downloads/)
 [![FastAPI](https://img.shields.io/badge/FastAPI-005571?style=flat&logo=fastapi)](https://fastapi.tiangolo.com/)
 [![Test Coverage](https://img.shields.io/badge/coverage-90%25-brightgreen.svg)](tests/)
-[![CI Tests](https://github.com/raold/second-brain/actions/workflows/test.yml/badge.svg)](https://github.com/raold/second-brain/actions/workflows/test.yml)
+[![CI Tests](https://github.com/raold/second-brain/actions/workflows/test.yml/badge.svg?branch=main)](https://github.com/raold/second-brain/actions/workflows/test.yml)
 
 > **🐳 Docker-First Development**: Zero host dependencies, bulletproof cross-platform development experience.