fix(game-store): guard against splice(-1) in processScuttle

[seriouslysean]

Found during a code audit.processScuttle() checks targetCardIndex === -1 before splicing but doesn't check playedCardIndex. If socket events arrive out of order and the played card is already missing from local state, splice(-1, 1) silently removes the last card in hand instead.

Added the same -1 guard that already exists for targetCardIndex.

Issue number

• N/A (found during code audit)

Please check the following

• Do the tests still pass?
• Is the code formatted properly?

Please describe additional details for testing this change

1. npm run test:unit
2. Hard to reproduce manually (requires socket race condition), but the guard matches the existing pattern for targetCardIndex right above it

[Copilot]

Pull request overview

This PR prevents hand corruption in the client game store by guarding against splice(-1, 1) when a scuttle event arrives and the played card is already missing from local state (e.g., socket event race/out-of-order delivery).

Changes:

• Add a playedCardIndex === -1 guard in processScuttle() to avoid removing the wrong card from hand.
• Fall back to updateGame(game) when local state is missing the played card, matching the existing targetCardIndex guard behavior.

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