bugfix: Update tableau visualization script to correctly parse get_zonemap() output

[kodiobika]

Summary

The Tableau visualization script was previously treating the outputs of reeds.io.get_zonemap() as having a nameless index, but it now has a name (r). As a result, the copying of relevant shapefiles was silently failing resulting in the visualization outputs containing no shapefiles.

Validation, testing, and comparison report(s)

I ran the script for the WY_county scenario and it now produces transmission_endpoints and US_PCA shapefiles.

General information to guide review

• Zero impact on results of default case
• No large data file(s) added/modified
• No substantive impact on runtime for full-US reference case
• No substantive impact on folder size for full-US reference case
• No change to process flow (runreeds.py, reeds/core/solve/solve.py)
• No change to code organization
• No change to package requirements (environment.yml or Project.toml)

Did you use LLM tools (chatbot or copilot) in the preparation of this PR? If so, describe how

No

Tag points of contact here if you would like additional review of the relevant parts of the model