🔍 Create a Prolog Expert System for Animal Classification

### 🐾 Prolog Expert System: Animal Classification

Create an expert system to classify an animal based on its traits (e.g., feathers, fur, lays eggs, etc.).

📁 Target file:
```

src/06_expert_system/animal_classifier.pl

```

Examples:
- Mammal
- Bird
- Reptile
- Fish

Use basic Prolog rules + facts and show a few sample queries in comments.

Start with src/06_expert_system/animal_classifier.pl and review the repository’s nearby expert-system examples, if any. Define facts and basic rules for the listed animal traits and classifications, then add several sample queries in comments. Done means the file classifies mammals, birds, reptiles, and fish from the demonstrated traits.

Written by the indexing model from the issue text.