Install jupyter-server-proxy in AoU Jupyter image

The /proxy/<PORT> URL path (used to access dashboards like Streamlit,
Dash, Shiny, etc.) works in non-AoU Jupyter apps but not in AoU. This
is because the AoU base image does not include the jupyter-server-proxy
package, which provides the reverse-proxy routing. Without it, requests
to /proxy/<PORT> fall through to the default JupyterLab handler.

The server-proxy-notif extension (already installed) detects listening
ports and shows proxy URLs, but it checks for jupyter-server-proxy at
runtime and returns empty results if missing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: github-actions

src/jupyter-aou/Dockerfile

@@ -1,5 +1,9 @@
 FROM us-west2-docker.pkg.dev/shared-pub-buckets-94mvrf/workbench-artifacts/app-aou-jupyter@sha256:54504cac626fa9ec61083b87e0c87f2d7859faf7a65830b2e8a743d6a08ac7a2
 
+# Enable /proxy/<PORT> routing so users can access dashboards and other
+# services running inside the container (e.g. Streamlit, Dash, Shiny).
+RUN pip install --no-cache-dir jupyter-server-proxy
+
 # Install jupyter extensions
 RUN --mount=type=bind,from=jupyter-extension-builder,source=/dist,target=/tmp/extensions \
     /tmp/extensions/setup.sh