Initial conditions for legoESM biophysics LMIP

Description: Spun-up global land initial condition for the legoESM differentiable Earth-system model's land-only (LMIP) biophysics configuration. This is the end-of-run land restart of a 10-year cold-start spin-up (forcing years 1975–1984, noleap calendar), so a warm-started run begins at the start of model year 1985 with equilibrated soil profiles instead of spending years drifting from a cold start. Configuration: legoESM at commit 14461553438f18d336985870770c38a4555d3552 (template biophysics/lmip_calibrated_spinup v1.0.0), forced by CRU-JRA v2.5 (the NCAR "filled Antarctica/Greenland" archive), CLM5-derived surface data (legoesm_surfdata_c260716.nc, Zenodo record 21401647). Physics: multilayer land with two-leaf canopy (Ball–Berry stomata), Monin–Obukhov surface exchange, Richards soil hydrology on a 10-layer / 3.0 m column, single-bulk snow, soil freeze/thaw, and the 2026-07 calibrated snow/glacier albedo and per-PFT root-zone parameters. Run at 1-hour steps in float64 on GPU. Contents: A compressed NumPy .npz holding, per land column of the 2° (90×180) grid: soil temperature, matric potential, and volumetric water content on the 10-layer column; surface and subsurface runoff stores; snow water equivalent and snow age; plus any active optional water reservoirs, and bookkeeping (restart schema version, land mode, model time reached, steps completed, JSON provenance metadata). It contains no carbon pools and no atmospheric state. Usage: Consumed by legoESM's run_lmip_biophys.py via --restart-from (or restart.from in the run config). The loader is strict: it refuses a mismatched land-column count, soil-layer count, land mode, or restart schema version, so the file is usable only on the exact grid and soil discretization above. See docs/land/lmip_biophys_soil_ic_spinup.md in the legoESM repository for the full runbook, end-state scorecard, and rebuild recipe. Known limitations: The ice-sheet snowpack is not physical: the snow scheme has no glacier sink, so Greenland/Antarctica accumulate ~3100 Gt/yr without ablation, reaching ~15 m water equivalent at the SE Greenland margin.