fix: resolve GGUF paths through HF cache, add model_id to GGUF config

llama-cpp-python backend now uses huggingface_hub to resolve GGUF
file paths within the HF cache structure instead of assuming flat
/models/ directory.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

kischdle/llmux/config/models.yaml

@@ -10,6 +10,7 @@ physical_models:
   qwen3.5-9b-fp8-uncensored:
     type: llm
     backend: llamacpp
+    model_id: "HauhauCS/Qwen3.5-9B-Uncensored-HauhauCS-Aggressive"
     model_file: "Qwen3.5-9B-Uncensored-HauhauCS-Aggressive-Q8_0.gguf"
     mmproj_file: "mmproj-Qwen3.5-9B-Uncensored-HauhauCS-Aggressive-BF16.gguf"
     estimated_vram_gb: 9