Add more diverse example YAML files

**Description:**
Create 5+ diverse project examples showing Arkify's versatility across different project types.

**Examples needed:**
- [ ] Mobile app project (React Native, Flutter, Swift)
- [ ] API/backend service (Node.js, Django, Rails)
- [ ] Chrome extension
- [ ] Open source library/package
- [ ] Freelance client work
- [ ] E-commerce site
- [ ] Developer tool/CLI

**Todo:**
- Create new YAML files in `examples/` folder
- Use real or realistic project data
- Include all required fields (name, hours, cost, tech_stack, learning)
- Optionally include extended fields (results, expectations vs reality)
- Test with: `python arkify.py examples/your-project.yaml`

**Good for:** First-time contributors, anyone who's built side projects!

**Template:**
```yaml
project:
name: "Your Project Name"
tagline: "One-line description"
hours: 42
cost: 100
tech_stack:
- "Tech 1"
- "Tech 2"
- "Tech 3"
- "Tech 4"
learning: "Your key insight"
```

See existing examples in `examples/` folder for inspiration!

Look at the existing YAML files in the `examples/` folder to understand the format. Create new files there for the requested project types, using realistic data. Test each file by running `python arkify.py examples/your-project.yaml` to ensure it works. The issue is done when you have added at least five new, diverse example files.

Rédigé par le modèle d'indexation à partir du texte de l'issue.