Refactor duplicated directional logic into helper methods

[Copilot]

The codebase contained repetitive if-statement patterns for handling directional inputs (left/right/up/down) across key handlers and movement logic.

Changes

Form1.cs

• Extracted HandleDirectionalKeyPress() - consolidates 4 if-statements into switch
• Extracted HandleDirectionalKeyRelease() - consolidates 4 if-statements into switch
• Extracted MoveZombieTowardPlayer() - encapsulates zombie AI movement

bullet.cs

• Extracted MoveBullet() - consolidates 4 if-statements into switch

Before

if (e.KeyCode == Keys.Left) {
    goLeft = true;
    facing = "left";
    player.Image = Properties.Resources.left;
}
if (e.KeyCode == Keys.Right) {
    goRight = true;
    facing = "right";
    player.Image = Properties.Resources.right;
}
// ... repeated for Up and Down

After

HandleDirectionalKeyPress(e.KeyCode);

private void HandleDirectionalKeyPress(Keys key) {
    switch (key) {
        case Keys.Left:
            goLeft = true;
            facing = "left";
            player.Image = Properties.Resources.left;
            break;
        // ... other cases
    }
}

Reduces duplication by ~100 lines with no behavioral changes.

Original prompt

Find and refactor duplicated code

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.