New Feature: Color Constellation

### Project slug (e.g., snake, todo)

_No response_

### Summary

Link stars to form constellations that match a given silhouette pattern. Links cannot cross.

**Acceptance Criteria:**

- Stars placed on a 2D plane.

- Click two stars to connect them.

- Check if resulting pattern matches target.

**Optional Enhancements:**

- Gravity slightly moves stars.

- Animated background (night sky gradient).

### Details / Acceptance criteria

_No response_

### Scope

- [ ] UI changes
- [ ] Logic changes
- [ ] Accessibility
- [ ] Tests (manual)