Extends the demographic/RUCA/energy summary with two new sections:
- §7 quantifies each top-DC state's "share of state capacity within
50 km of a DC," surfacing NJ (83%), NV (75%), TN (70%), and OR (68%)
as the most DC-saturated grids — reframing the canonical VA-centric
story by structural entanglement rather than raw count.
- §9 inventories every table in the data_centers schema with a
one-line description, flagging cleanup candidates and unused layers
for downstream work.
Also renumbers watershed analysis to §8, adds the SEDS row to the
dataset coverage table, and narrows next-step #4 to the IM3 projection
overlay (now that the SEDS join is complete).
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
