[JonasFocus]

Summary

When every live player is all in before the river, the table can agree to run the board twice and split the pot by runout.

Changes

• Engine: when the betting ends with at most one player able to act and the board is not complete, everyone in the pot gets a 5 second "Run it twice?" prompt. It runs twice only if every player says yes; any no or an expired timer deals once as before.
• Each pot, side pots included, is split in half by board, with the odd chip on the first board. An uncalled bet is still returned whole. Results carry the second hand, and win rows and card highlights follow the board each player won on.
• A host toggle in the lobby (on by default), new setRunTwice and runTwice intents with strict parsing, and a Yes / No prompt in the action panel.
• Both boards are shown stacked on the felt, and the second board only exists in state once its cards are dealt, so no undealt card reaches a client.

Why

Closes #60. A common home-game option for all-ins before the river, behind a setting so it never surprises a table.

Testing

• New engine tests: prompt, toggle, host and lobby only, unanimous yes, a no, timeout, voting rules, split by board, side pots, odd chip, flop and preflop all-ins, redaction, intent parsing, and a 200 hand fuzz for chip conservation.
• Manual run against a local server and dev build with a scripted opponent: the prompt appeared, Yes ran both boards, and the layout measured clear of the pot and the win banner.
• lint, typecheck, test and build pass.

Notes

• Bots always agree and are never asked. Nobody is asked if a human in the pot is offline, since they cannot answer.
• The second board repeats the shared cards, so the shared flop deals in again on the second row.