feat: Phase A NetCDF forcing validation pass (10-day QHH)

[DankerMu]

Summary

Phase A (NetCDF Forcing) 验证通过。NetcdfForcingProvider 直接读取 CMFD2 NetCDF 原始文件，与 AutoSHUD 生成的 baseline CSV forcing 完全一致。

Changes

projects/qhh/shud.yaml

• nc profile: add forcing.kv.CMFD_PRECIP_UNITS: MM_HR override
• nc profile: set output_mode: legacy for Phase A validation

tools/shudnc.py

• render-shud-cfg: support forcing.kv dict for arbitrary KEY VALUE overrides in cfg.forcing

tools/compare_forcing.py

• Add CSV quantization matching (precip 4dp, temp 2dp, RH 4dp, wind 2dp, radiation int)
• Support CMFD_PRECIP_UNITS override from cfg.forcing

SHUD submodule

• Updated ref → DankerMu/SHUD-up PR #78 (off-by-one fix + quantization matching)

Verification Results

10-day QHH run (END=730, START=1):

Metric	Result
Forcing diff (5 vars)	max_abs = 0 (exact match)
Output .dat binary diff	IDENTICAL (md5sum match)
Baseline rerun (NETCDF=1 binary)	Output unchanged

Dependencies

• SHUD submodule: fix: NetCDF forcing month-range off-by-one + CSV quantization matching SHUD-up#78

[DankerMu]

Review: SHUD-NC PR #36

shud.yaml

kv: CMFD_PRECIP_UNITS: MM_HR and output_mode: legacy are correct for Phase A validation.

shudnc.py render-shud-cfg kv support

Input validation is thorough (type check, null, whitespace). Keys uppercased. Appended after adapter defaults allowing override.

compare_forcing.py

_cmfd2_precip_units_kind_from_cfg() mirrors C++ CMFD_PRECIP_UNITS logic. Quantization matches C++ side exactly.

SHUD submodule ref

Points to PR #78 commit (off-by-one fix + quantization).

Verification

10-day QHH: all 5 forcing vars max_abs_diff=0, output .dat binary identical, baseline unbroken.