[codex] support NHC temperature ramps

[klxuyfk]

Summary

• add Nose-Hoover chain temperature ramp updates for MDALGO=2 and MDALGO=4
• parse VASP-style NHC_PERIOD and convert it to ASE damping time as NHC_PERIOD * POTIM
• add clear runtime errors for incompatible ASE NHC internals, disabled NHC chain settings, and non-positive NHC temperatures
• document the Python API, INCAR tags, and CLI behavior for NHC ramps

Root Cause

ASE NoseHooverChainNVT in current environments does not expose set_temperature(), while VPMDK's ramp updater expected thermostat drivers to support it. That made TEEND temperature ramps fail for Nose-Hoover chain runs after the first MD step.

Impact

Users can now run positive-temperature TEBEG to TEEND ramps with VPMDK's Nose-Hoover chain path. If the installed ASE version lacks both set_temperature() and the expected compatible internal thermostat state, VPMDK raises a clear error instead of surfacing an AttributeError.

Validation

• pytest -m "not integration" -q
• short real-ASE smoke run with MDALGO=4, TEEND != TEBEG, NHC_PERIOD, and NHC_NCHAINS completed successfully

[klxuyfk]

I checked that it's implemented colectly