Drop harbor from requirements to fix the Docker build

harbor>=0.6.0 requires Python >=3.12 but the image is python:3.11-slim,
and it's only used as a CLI for harbor:// URIs (shelled out, not imported).
The core HF/GitHub/local viewer needs none of it.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

requirements.txt

@@ -1,4 +1,8 @@
 fastapi>=0.115
 uvicorn[standard]>=0.30
 huggingface_hub>=0.27.0
-harbor>=0.6.0
+# `harbor` is intentionally NOT a dependency: it's only used to fetch
+# `harbor://` registry datasets (via the CLI, shelled out in viewer/load.py),
+# requires Python >=3.12, and pulls in a heavy dep tree. The core viewer
+# (HF Hub / GitHub / local) needs none of it. To enable harbor:// support,
+# add `harbor>=0.6.0` here and bump the Dockerfile base image to python:3.12.