Behind-the-Meter Solar at Hyperscale Data-Center Campuses: A Resource-Graded Carbon-Price Threshold Across Eleven U.S. Markets (code and data)

Adds src/build_multisite.py, which assembles data/results_multisite.csv from the model outputs, closing the last manual step between model output and Figures 3 and 4. Adds Makefile targets for the merged table and a check mode. Model code, input profiles and model outputs are otherwise unchanged from v1.0.0.