[FEATURE] Convert Hard-Coded Globals to Godot Resource

[ikostan]

Description:
Convert hard-coded globals in globals.gd (e.g., difficulty=1.0, volumes=1.0) to a Godot Resource for centralized config.

Why is this useful?

• Learning Godot: Global resources for settings.
• Extensibility: Easy mode/difficulty switches.
• Balancing: Volume/difficulty tweaks without code.

Proposed Implementation:

1. Create SettingsConfig.tres with fields: difficulty (1.0), master_volume (1.0), audio_buses.
2. Load in Globals.gd _ready(): var settings = load("res://resources/SettingsConfig.tres").
3. Replace constants with settings.difficulty, etc.
4. Apply in game logic (e.g., enemy scaling).

Additional Context:
Supports options menu; aligns with audio buses.