docs: Add comprehensive README with project overview and alternatives

- Add project description and philosophy
- Document why not use local proxy, LiteLLM, or advanced features
- Add "Not Suitable For" section with alternatives
- Add link to cheap LLM providers repo

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -1,2 +1,31 @@
-# claude-central-gateway
-Claude Central Gateway, proxy your Claude Code request to 3rd provider that you want, can easy hosted on Vercel, Netlify,...
+# Claude Central Gateway
+
+A proxy for Claude Code that routes requests to your preferred third-party API provider. Easily hosted on Vercel, Netlify, and similar platforms.
+
+## Where to Find Cheap LLM Providers?
+
+Check out [this repo](https://github.com/tiennm99/penny-pincher-provider) for a list of affordable LLM providers compatible with this gateway.
+
+## Philosophy
+
+Minimal, simple, deploy anywhere.
+
+## Why This Project?
+
+### Why not use a local proxy, like [Claude Code Router](https://github.com/musistudio/claude-code-router)?
+
+Local proxies only work on a single machine. This project serves multiple machines simultaneously.
+
+### Why not use [LiteLLM](https://github.com/BerriAI/litellm)?
+
+LiteLLM requires a dedicated VPS, consumes more resources, and costs more to deploy.
+
+### Why no advanced features like routing or GUI management?
+
+Built for personal use. Simplicity over features.
+
+## Not Suitable For
+
+- **Single-machine localhost proxy** → Highly recommend [Claude Code Router](https://github.com/musistudio/claude-code-router)
+- **Enterprise/Team usage with GUI management** → Use [LiteLLM](https://github.com/BerriAI/litellm)
+- **Advanced routing, load balancing, rate limiting** → Use [LiteLLM](https://github.com/BerriAI/litellm) or similar