feat: implement Level 7 and configure webpack build modes

[MuhammadAhmadF2005]

Title

feat: implement Level 7 and configure webpack build modes

Description

This PR adds a new, challenging level (Level 7) to the game progression and resolves webpack dev-server configuration warnings.

Key Changes

1. Added Level 7 Gameplay Configuration

• File: src/data/levels.json
• Settings:
  • Waves: 3
  • Ducks: 4 (simultaneous spawn for high-intensity gameplay)
  • Points per Duck: 150
  • Speed: 9 (faster and more challenging movement profile)
  • Bullets: 6 (offering a buffer of two missed shots for 4 ducks)
  • Time: 12 seconds per wave

2. Webpack Development Server Optimization

• File: package.json
• Changes:
  • Added explicit --mode development to npm start (webpack-dev-server) to remove the fallback warnings and improve the browser overlay feedback.
  • Added explicit --mode production to npm run build to ensure production compilation assets remain fully optimized.

3. Rebuilt Production Assets

• Updated and compiled the final output files in dist/ accordingly.

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Verification and Testing

• Linting: Verified code style cleanliness using npm run lint.
• Build Output: Verified error-free bundling using npm run build.
• Gameplay: Manually verified level load state, wave progression, and bullet count in local dev environment at http://localhost:8080/.