Added Requesty as a provider

Requesty is an OpenAI compatible AI gateway. The provider mirrors OpenRouter: chat completions over https://router.requesty.ai/v1/, the same project headers, and a model list read from both the managed policies (models/managed) and the full catalog (models), including the context window.

app/MindWork AI Studio/Provider/LLMProvidersIconExtensions.cs

@@ -31,6 +31,7 @@ public static class LLMProvidersIconExtensions
         LLMProviders.HETZNER => $"{ICON_ROOT}/hetzner.svg",
         LLMProviders.IONOS => $"{ICON_ROOT}/ionos.svg",
         LLMProviders.LITE_LLM => $"{ICON_ROOT}/litellm.svg",
+        LLMProviders.REQUESTY => $"{ICON_ROOT}/requesty.svg",
         LLMProviders.GROQ => $"{ICON_ROOT}/groq.svg",
         LLMProviders.FIREWORKS => $"{ICON_ROOT}/fireworks.svg",
         LLMProviders.HUGGINGFACE => $"{ICON_ROOT}/hugging-face.svg",