V145 - Global 6h amplitude decay retuned to 22.5%

Baseline: v144_visible_depth_export_compile_fix.

Change:
- GLOBAL_HEIGHT_DECAY_KEEP_6H changed from 0.940 to 0.775.
- This means global amplitude loss is 22.5% per 6 hours.
- No other temporary damping or shoaling changes were added.

Kept from v144:
- Map/max-wave output no longer applies extra depth^-0.25 shoaling.
- Station/JESIM shoreline-equivalent 1 m conversion is kept.
- Face-depth flux clean solver path is kept.
- CSV Dip-all, station 1500/1501/1502/1524 -> ID 49, and shallow-coast damping removal are kept.
