Fix infinite loop when less than 2 players

[twt1978]

This PR fixes the infinite loop issue described in #28.

Problem:
If the user enters "!" immediately when prompted for player names, the game will enter an infinite loop when prompted for an imposter count.

Solution:

• Added validation to ensure at least 2 players before proceeding
• Prevents infinite loop in imposter count selection
• Maintains game flow while ensuring proper player count

Changes:

• Added a while loop after player collection that ensures at least 2 players
• User is prompted to add more players until minimum count is satisfied
• Preserves existing game logic and user experience

Testing:

• Tested with 0 initial players (prompts for at least 2)
• Tested with 1 initial player (prompts for one more)
• Tested with 2+ initial players (proceeds normally)

Fixes #28