fix: hide opponent hand when rematching a reopened finished game

[SamuelHetes]

Issue number

• Resolves [Bug]: Opponent hand sometimes revealed on starting a rematch game #1385

Reopening a finished game joined the original player to the spectator socket room, causing their next rematch to reveal the opponent's hand. Keep players in their p0/p1 rooms in both game-loading and spectate actions, while preserving full visibility when viewing finished games.

Please check the following

• Do the tests still pass?
• Is the code formatted properly?
• For New Features:
  • Have tests been added to cover any new features or fixes?
  • Has the documentation been updated accordingly? (N/A: bug fix with no new user-facing workflow.)

Please describe additional details for testing this change

1. Start a game with two accounts and concede.
2. Go Home, then reopen the finished game via its URL or browser Back.
3. Accept a rematch with both accounts. The opponent's hand should stay hidden, including after their next draw.

Added Cypress regressions for both navigation paths and 20 controller unit tests covering player/spectator rooms, visibility, and live-game self-spectating restrictions. The URL regression failed before the fix and passed afterward.

Validation on Node 22.21.1: lint and build passed; all 106 unit tests passed. All 34 standard E2E specs were run: final results were 387 passed and 5 existing pending tests. One game-creation setup timeout in live-spectating.spec.js passed on an isolated rerun of the entire spec (12/12), without code changes. GitHub CI remains to be run.

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[itsalaidbacklife]

Great work. Thanks for the fix! One nitpick on the e2e test and then this is ready

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