Create appuser for UID 1000 to fix PyTorch getpwuid KeyError

Dockerfile

@@ -23,12 +23,14 @@ RUN python -c "from sentence_transformers import SentenceTransformer; SentenceTr
 # Copy application code
 COPY . .
 
-# Create data directories and fix ownership for HuggingFace Spaces (runs as UUID 1000)
-RUN mkdir -p data chroma_db logs && \
-    chown -R 1000:1000 /app
+# Create data directories and user for HuggingFace Spaces (runs as UUID 1000)
+# PyTorch requires a named user in /etc/passwd, otherwise getpass.getuser() throws a KeyError
+RUN useradd -m -u 1000 appuser && \
+    mkdir -p data chroma_db logs && \
+    chown -R appuser:appuser /app
 
 # Specify user for HF Spaces
-USER 1000
+USER appuser
 
 # Expose ports for backend (8000) and frontend (7860 = HF Spaces default)
 EXPOSE 7860 8000