Fix UI/UX issues and Improve save/load system.

- Add all currency fields (metalScrap, titaniumCore, neurochip) to new save template
- Redesign save dialog UI with wooden theme matching game aesthetic
- Fix ESC key and pause button to properly open pause menu
- Fix pause menu layering - save dialog now appears on top
- Update win/lose conditions to use homebase health instead of player health
- Fix entity cleanup timing to ensure score calculation works correctly
- Merge latest changes from main branch

Author: iixuo

source/core/assets/flat-earth/skin/flat-earth-ui.json

@@ -30,29 +30,29 @@ com.badlogic.gdx.graphics.Color: {
 		a: 1
 	}
 	color: {
-		r: 0.3372549
-		g: 0.8
-		b: 0.44705883
+		r: 1,
+		g: 0.549,
+		b: 0,
 		a: 1
-	}
+	},
 	gray: {
 		r: 0.5
 		g: 0.5
 		b: 0.5
 		a: 1
 	}
 	highlight: {
-		r: 0.42156863
-		g: 1
-		b: 0.5552286
+		r: 1,
+		g: 0.7,
+		b: 0.3,
 		a: 1
 	}
 	pressed: {
-		r: 0.2529412
-		g: 0.6
-		b: 0.33313715
+		r: 0.8,
+		g: 0.4,
+		b: 0,
 		a: 1
-	}
+	},
 	selection: {
 		r: 0.22745098
 		g: 0.59607846

source/core/assets/images/book.png

@@ -244,6 +244,12 @@ private void buildSpawnQueue() {
     public void onWaveDefeated() {
         logger.info("Wave {} defeated!", currentWaveIndex + 1);
 
+        // Safety check: if waves not initialized (e.g., loaded from save), don't process wave progression
+        if (waves == null) {
+            logger.warn("Waves not initialized - skipping wave progression");
+            return;
+        }
+
         // Check if this was the final wave
         if (currentWaveIndex + 1 >= waves.size()) {
             // All waves complete - trigger victory!