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/Projectile.java

@@ -0,0 +1,16 @@
+import javax.swing.ImageIcon;
+
+public class Projectile extends Collidable {
+  int xVelo;
+
+  public Projectile(int x, int y, int w, int h, int curLevel, int direction) {
+    super(
+        x, y, w, h, new ImageIcon("Sprites/Projectiles/" + ((curLevel == 1) ? "1" : "2") + ".png"));
+    xVelo = 10 * direction;
+  }
+
+  public void move() {
+    this.x += xVelo;
+    this.rect.x = this.x;
+  }
+}