SHA-256 dedup hash from sync_fio_to_sheets.py generate_sync_id.
Key subtlety: Python str(float) emits "500.0" for whole-valued floats
and switches to scientific notation at |f|>=1e16 or |f|<1e-4 —
replicated via formatAmount using 'f'/'e' format selection.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
