fix: switch HF endpoint to universal router URL (auto-selects provider)

Dockerfile

@@ -15,7 +15,7 @@ RUN pip install --no-cache-dir -r requirements.txt
 
 # Cache-bust: forces Docker to re-copy source code on every build
 # This ensures HuggingFace always gets the latest code from git
-ARG CACHEBUST=20260414_3
+ARG CACHEBUST=20260414_4
 
 # Copy source code
 COPY src/ ./src/

src/rag/llm_client.py

@@ -55,7 +55,7 @@ class MultiModelClient:
         if not self.hf_api_key:
             raise ValueError("HF_API_KEY not configured")
 
-        url = f"https://router.huggingface.co/hf-inference/models/{model_id}/v1/chat/completions"
+        url = "https://router.huggingface.co/v1/chat/completions"
         headers = {
             "Authorization": f"Bearer {self.hf_api_key}",
             "Content-Type": "application/json"