PG&E circuit ID to location mapping.

Each 9-digit representative circuit ID encodes a PG&E distribution feeder:
region, division, substation, and feeder number.

Data derived from:
- PG&E 2022 Grid Needs Assessment (CPUC filing 496629893, Appendix D)
- Priicer community cross-reference
  (https://forum.priicer.com/t/pg-e-dynamic-pilot-california/33)

PG&E-specific GridX Pricing API client.

Wraps `gridx.client` with PG&E defaults: utility, market, program,
and API URLs. The OpenAPI spec at `gridx-pricing-spec/pge/openapi.yaml`
defines the available rate schedules and circuit IDs.

Required params for `get-pricing`:
  :startdate               - "YYYYMMDD" (earliest 20240601)
  :enddate                 - "YYYYMMDD" (max ~2 weeks span)
  :ratename                - PG&E rate schedule code (e.g. "EELEC")
  :representativeCircuitId - 9-digit feeder ID (see gridx.pge.circuits
                             for location lookup)

Optional params:
  :cca                     - CCA code (e.g. "AVA", "PCE")

Use `gridx.pge.circuits/find-circuits` to look up circuit IDs by
substation name, e.g. (find-circuits "mountain view").