Add initial implementation of game mechanics and resources management

Scripts/Core/Effects/ApplyBuffEffect.cs

@@ -0,0 +1,24 @@
+using Godot;
+
+namespace ParasiticGod.Scripts.Core.Effects;
+
+[GlobalClass]
+public partial class ApplyBuffEffect : Effect
+{
+    public enum BuffTarget { FaithGeneration }
+    
+    [Export] public BuffTarget TargetStat { get; set; }
+    [Export] public float Multiplier { get; set; } = 2.0f;
+    [Export] public double Duration { get; set; } = 30.0;
+    
+    public override void Execute(GameState gameState)
+    {
+        var newBuff = new Buff
+        {
+            Multiplier = Multiplier,
+            Duration = Duration
+        };
+        
+        gameState.ActiveBuffs.Add(newBuff);
+    }
+}