[US-04] Playing alone against the computer
Implements single-player mode with AI opponent featuring:
- AI ship placement with validation (no overlaps, within boundaries)
- Two difficulty levels: Easy (random shots) and Normal (hunting mode)
- Computer opponent that never shoots at the same coordinate twice
- Hunting mode in Normal difficulty that targets adjacent cells after hits
- Complete integration with existing game flow
Closes #4
Edited by Ivan Esau