Organize game files into their project directory and ensure proper build configuration

Moves all game source files and assets into the 'American-Identity-Project' directory and updates the manifest to point to the 'Display' class as the main entry point.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: f6819c21-e85d-45ac-acde-604db2cfa4fe
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Event-Id: a9500e48-7f68-408f-a5c6-28df9f59fe00
Replit-Helium-Checkpoint-Created: true

American-Identity-Project/Enemy.java

@@ -0,0 +1,53 @@
+import java.util.*;
+import javax.swing.ImageIcon;
+
+public class Enemy extends Collidable {
+  int xVelo, yVelo;
+  boolean alive;
+
+  public Enemy(int x, int y, int w, int h, int level) {
+    super(x, y, w, h, new ImageIcon("Sprites/Enemies/" + level + ".png"));
+    xVelo = 2;
+    yVelo = 0;
+    alive = true;
+  }
+
+  public void moveX(int moveX) {
+    this.x += moveX;
+    this.rect.x = this.x;
+  }
+
+  public void moveY(int moveY) {
+    this.y += moveY;
+    this.rect.y = this.y;
+  }
+
+  public void patrol(ArrayList<Collidable> collidables) {
+    moveX(xVelo);
+
+    for (Collidable c : collidables) {
+      if (this.collidesWith(c)) {
+        xVelo = -xVelo;
+        moveX(xVelo * 2);
+        break;
+      }
+    }
+
+    // check edge detection - is there ground below next step?
+    boolean edgeAhead = true;
+    int nextX = this.x + xVelo;
+    for (Collidable c : collidables) {
+      if (c instanceof Tile) {
+        Tile t = (Tile) c;
+        // check if tile is below enemy's next position
+        if (nextX + this.width > t.x && nextX < t.x + t.width && t.y == this.y + this.height) {
+          edgeAhead = false;
+          break;
+        }
+      }
+    }
+    if (edgeAhead) {
+      xVelo = -xVelo;
+    }
+  }
+}