rename an example, add image generation example

Author: leafo

examples/image_generation.lua

@@ -0,0 +1,36 @@
+
+
+local openai = require("openai")
+local client = openai.new(os.getenv("OPENAI_API_KEY"))
+
+local status, response = client:image_generation({
+  model = "gpt-image-1.5",
+  prompt = "Design a modern logo for MoonScript, the language that compiles to Lua"
+})
+
+
+if status == 200 then
+  print("Size", response.size)
+  print("Background", response.background)
+  print("Output format", response.output_format)
+  print("Quality", response.quality)
+
+  -- output the image
+  local filename = "image_generation.png"
+  local mime = require("mime")
+  local image_bytes = mime.unb64(response.data[1].b64_json)
+
+  local file = io.open(filename, "wb")
+  if file then
+    file:write(image_bytes)
+    file:close()
+    print("Saved image to: " .. filename)
+  else
+    print("Failed to save image to: " .. filename)
+  end
+else
+  local json = require("cjson")
+  print(json.encode(response))
+end
+
+