Add documentation for LLMProxy, a high-performance LLM reverse proxy with
zero-buffer streaming, native token metering, and load balancing support.
Changes:
- Add docs/providers/llmproxy.md with full setup guide
- Add LLMProxy to providers index (Community tools section)
- Add LLMProxy section to model-providers.md
Co-Authored-By: Warp <agent@warp.dev>
