feat: set Llama 3 8B as recommended default model

fix: use router.huggingface.co to bypass DNS failure on HF Spaces, default to Qwen 2.5

fix: use router.huggingface.co to bypass DNS failure on HF Spaces, default to Qwen 2.5

fix: use InferenceClient directly to fix DNS error on HF Spaces, add search retry/fallback

fix: use InferenceClient directly to fix DNS error on HF Spaces, add search retry/fallback

fix: DuckDuckGo rate limit handling with retry and fallback

Initial commit — NeuroResearch Multi-Agent System