Commit match.result, under_over_result, and winning_outcomes atomically to
the DB before sending PLAY_VIDEO_MATCH. A crash after this commit always
recovers the same outcome on restart; before this fix, killing the process
between extract_match() and the bet-settlement commit re-rolled the random
draw on each restart, allowing an attacker to loop until a desired outcome
was selected.

Also adds an idempotency guard at the top of _handle_match_start: if the
result is already committed (crash between lock and settlement), bets are
re-settled from the stored result without re-extraction.

Replaces the random fallback in _handle_play_video_match_done with a DB
lookup of match.result, which is now always committed before the video
player is signalled.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>