Updates for the new ismip7 cism source branch

[Katetc]

The PR ESCOMP/CISM/pull/91 is bringing in a lot of changes for the ISMIP experiments this month. We will need a CISM-Wrapper tag and updates to the namelist for these changes.

Claude went through the PR and came up with these namelist changes to support the new code:

Summary

PR #91 renames several CISM config-file keys and changes a few defaults as part of a
larger rewrite of basal friction, isostasy, and lateral-melt handling. None of the
renames have a backward-compatible alias, so any CESM namelist/config template that
still uses the old key names will have those settings silently ignored (the model
will fall back to the new default rather than erroring). We need to update the CESM-side
config templates and re-verify any experiments that rely on the affected options.

Renamed keys (old → new)

These need to be updated in all CESM config templates / user_nl files that set them:

• coulomb_c_const_hi → coulomb_c_hi
• coulomb_c_const_lo → coulomb_c_lo
• whichrelaxed → which_relaxed
• relaxed_tau → tau_relax_const
• lithosphere_period → load_update_interval

Default value changes (relevant even if the key name is updated correctly)

Parameter	Old default	New default
tau_relax_const (was relaxed_tau)	4000 yr	3000 yr
load_update_interval (was lithosphere_period)	100 yr	10 yr
coulomb_c_lo (was coulomb_c_const_lo)	0.10	0.05

Action: any CESM template currently relying on the old default (i.e., not setting
these explicitly) should decide whether to pin the old value explicitly or adopt the
new default going forward.

Options removed — check for usage in CESM configs

• which_ho_babc = 3 ("modified Schoof friction law" / HO_BABC_MODIFIED_SCHOOF) — removed entirely.
• which_ho_coulomb_c = 4 ("read basin-scale coulomb_c_hi/lo from file" / HO_COULOMB_C_EXTERNAL_BASIN) — removed entirely.
• ocean_p_timescale — config key removed with no replacement (the relaxation-toward-target scheme it controlled was removed).
• which_ho_flotation_function = 3 ("modified linear, with topg_raised") — removed; the associated topg_raised output field is also gone.
• coulomb_c_hi/coulomb_c_lo as spatially-varying 2D input fields — no longer supported; these are scalar constants only now.

If any CESM compsets/templates set these, they'll need a config redesign, not just a
key rename.

New options available (optional follow-up, not blocking)

• which_lateral_melt (+ new [lateral_melt] section: melt_rate_const, melt_factor,
  subglacial_discharge_from_ablation, thermal_forcing_avg_3d_to_2d, ztop_tfavg, zbot_tfavg)
• schoof_n, schoof_gamma, schoof_p
• inversion_damping_factor
• bpmp_threshold, haf_threshold (default 500 m)
• bmlt_float_init
• New enumerated values for which_ho_powerlaw_c (4), which_ho_calving_front (2),
  and which_ho_deltaT_ocn (4, 5)

To verify before closing this issue

• Confirm whether CISM's config parser flags unrecognized keys as an error/warning,
  or silently ignores them — this determines how urgently existing CESM templates
  need auditing.
• Grep all CESM CISM config templates and any documentation/user guides for the
  five renamed keys above.
• Re-run any CESM test suites / spin-ups that use elevation_based_coulomb_c,
  isostasy with a relaxing mantle, or basin-scale Coulomb/powerlaw inversion, since
  these are affected by both the renames and some accompanying physics changes in
  PR Change Clm50 tests in the testlist to Clm60 #91 (see PR review discussion for details on the basin-scale inversion mask
  changes).
• Double check the which_ho_effecpress option numbering — the printed option
  descriptions were reordered in PR Change Clm50 tests in the testlist to Clm60 #91 and it's not yet confirmed whether the
  underlying option values were renumbered to match.

References

• ESCOMP/CISM/pull/91 (full diff reviewed in accompanying code review notes)