Add a straddle from any non-blind seat (default 2×BB) via a preflop control.
Recorded as a preflop post (fits the contract — order carries 'acts last'), tagged
straddle for the log label + removability; the UI-only flag is dropped from the
emitted structured hand. Blinds stay non-removable. Documented in HAND_HISTORY.md.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>