Animate card movement and fix game state issues

[jgarber]

Summary

• Animate local draw/discard actions and other players' draw/discard activity.
• Initialize round players from the incoming game payload so table target areas render correctly at game start.
• Clear the stored user id when the matching keychain token is missing or removed to avoid stale identity checks.

Coding assistance by Codex.

Test Plan

• xcodebuild -project Level10.xcodeproj -scheme "Level10 Debug (Development)" -configuration "Debug (Development)" -destination "platform=iOS Simulator,name=iPhone 17" build