Canyon_geometry

Weighted-average internal building temperature from canyon and roof surface temperatures, implementing Oleson et al. (2010, CLM Tech Note Ch. 4) Eqs. 4.37–4.38. The roof length L_roof in an infinite canyon (Eq. 4.38) and the unclamped building temperature T_iB_unclamped (Eq. 4.37) are both algebraic functions of the canyon geometry (H_canyon, H_W, W_roof) and the inner-surface temperatures of the shaded wall, sunlit wall, and roof. T_iB is the area-weighted average with the two walls contributing 2*H_canyon of effective length and the roof contributing L_roof. Migrated from UrbanCanopy.jl@9200edd4 src/roof_wall_road_snow_temperatures.jl:401 (`BuildingTemperature` @component). NOTE: the migration-tracker entry listed `blocking_gap: other:discretization-plan` citing line :1152, but that line belongs to `RoofWallHeatConduction` (a separate non-exported helper function). `BuildingTemperature` itself is a pure two-equation algebraic `@component` with no PDESystem or MOLFiniteDifference — this migration is unblocked.