Allow removing players/CPUs at any count during setup

[lchoward]

Summary

• Removed the game.players.length > 2 guard on the remove button in SetupScreen
• The × button now appears next to every player/CPU row regardless of player count, so users can always remove a player or CPU during setup

Fixes FLI-17

Test plan

• Start a new game, add 1 player — × button should appear
• Add 2 players — both should have × buttons
• Remove a player with 2 players — should go down to 1
• Verify "Start Game" still requires 2+ players with names

🤖 Generated with Claude Code

[linear]

FLI-17 add back ability to remove a player/cpu