透過 OpenRouter API 生成圖片，支援 Flux、Gemini、GPT-5 Image 等多種模型。需要 OPENROUTER_API_KEY 環境變數。
Generate images using OpenRouter's API (Flux, Gemini, GPT-5 Image models). Use when the user asks to generate, create, or make an image, thumbnail, illustration, or visual.
