Slice 2 of the Solar PV Recommendation Generator (ADR-0026). Adds the
strictly-typed `SolarPotential` domain projection over the raw Google Solar
`buildingInsights` JSON that Ingestion persists (SolarRepository): the
`solarPanelConfigs` ladder, each rung broken into its roof segments with
Google's continuous azimuth/tilt mapped to the SAP octant
(`azimuth_to_sap_octant`, 0°=N clockwise → 1=N..8=NW, matching the
calculator's ORIENTATION_BY_SAP10_CODE) and RdSAP §11.1 pitch code
(`pitch_to_sap_code`, snap to {0→1,30→2,45→3,60→4,90→5}).
Pinned against the real London buildingInsights example (mirrored into
fixtures from the user-provided RTF): 400 W panels, maxArrayPanelsCount 49,
46-rung ladder, per-segment SE/NW/NE/SW octants at ~32° → pitch code 2.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
