fix: add root Dockerfile for HF Spaces (requires Dockerfile at repo root)

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

Dockerfile

@@ -0,0 +1,25 @@
+FROM python:3.11-slim
+
+# HF Spaces requires user ID 1000
+RUN useradd -m -u 1000 user
+WORKDIR /home/user/app
+
+# Copy source and install
+COPY --chown=user pyproject.toml .
+COPY --chown=user agent_bench/ agent_bench/
+COPY --chown=user configs/ configs/
+COPY --chown=user data/ data/
+COPY --chown=user scripts/ scripts/
+
+RUN pip install --no-cache-dir .
+
+# Pre-download models at build time
+RUN python -c "from sentence_transformers import SentenceTransformer; SentenceTransformer('all-MiniLM-L6-v2')"
+RUN python -c "from sentence_transformers import CrossEncoder; CrossEncoder('cross-encoder/ms-marco-MiniLM-L-6-v2')"
+
+# Run ingestion at build time so the store is ready
+RUN python scripts/ingest.py --doc-dir data/tech_docs/ --store-path .cache/store
+
+USER user
+EXPOSE 7860
+CMD ["uvicorn", "agent_bench.serving.app:create_app", "--factory", "--host", "0.0.0.0", "--port", "7860"]