Wind_limit

Maximum effective wind speed (U_limit) above which the wind factor in the Rothermel surface fire spread model saturates. Migrated from WildlandFire.jl@126976f2 src/rothermel.jl:465 (`WindLimit` @component). Observed-only: IR is the input parameter; U_limit is the algebraic output. Both upstream branches are preserved here as a single `ifelse` on the dimensionless `use_corrected` indicator parameter — corrected (Andrews et al. 2013) when use_corrected > 0.5 (the upstream default), original when use_corrected ≤ 0.5. Implements Eq. Ulimit, Table 7 in Andrews (2018) RMRS-GTR-371.