add openrouter example

Author: leafo

README.md

@@ -8,6 +8,9 @@ with OpenResty using
 This project implements both the classic Chat Completions API in addition to
 the modern Responses API.
 
+Compatibility clients for [Google Gemini](#using-with-google-gemini) and
+[OpenRouter](#using-with-openrouter) are also included.
+
 <details>
 <summary>AI Generated Disclaimer</summary>
 

examples/openrouter/basic.lua

@@ -0,0 +1,20 @@
+-- Example: Using OpenRouter with chat completions
+-- Requires OPENROUTER_API_KEY environment variable
+
+local OpenRouter = require("openai.compat.openrouter")
+local client = OpenRouter.new(os.getenv("OPENROUTER_API_KEY"))
+
+local status, response = client:create_chat_completion({
+  {role = "user", content = "Write a haiku about Lua programming"}
+}, {
+  model = "xiaomi/mimo-v2-flash:free"
+})
+
+if status == 200 then
+  print(response.choices[1].message.content)
+else
+  print("Error:", status)
+  if response and response.error then
+    print(response.error.message)
+  end
+end