Create Health Management System

[Junaid-Kureshi]

Implement player and dealer health management functions in GameManager.gd.

Requirements:

• Complete damage_player(), damage_dealer(), heal_player(), heal_dealer() functions
• Implement health bounds checking (0 to max_health)
• Emit health_updated signal when health changes
• Add _check_game_end() logic to detect win conditions
• Call end_game() when a player reaches 0 health

Acceptance Criteria:

• Health cannot go below 0 or above max_health
• Signals emit correctly with current health values
• Game ends when health reaches 0
• Both healing and damage work properly

Files to modify:

• scripts/singletons/GameManager.gd

Testing:
Manually call damage/heal functions in console and verify UI updates.