feat(providers): add OVHcloud, STACKIT, Nscale; fix Mistral & Nebius fetchers

fix: propagate model capabilities globally and add missing icons for Whisper/Voxtral

feat: comprehensive audio/multimodal pricing support and improved model metadata enrichment (Whisper, Gemini 3.1, Voxtral)

fix: implement robust fetching with retries and exponential backoff for benchmarks and providers

init