Perft implementation

[Hardcode3]

📌 Perft implementation

📄 Description

• Implemented perft and perft_divide to debug move generation until depth 6
• Added tests to run perft on a regular basis
• Added custom tests flags to separate perft tests with depth <= 3, depth = 4 & 5 and depth >= 6
• Added new ctest presets:
  • quick validation: within seconds
  • intermediate validation: within the minute
  • deep validation: within the hour
  • full suite: all the available tests
• Updated workflows to use the quick validation test preset
• Updated cmake documentation in doc/
• Fixed a bug where a pawn that generated en passant while giving check to the opponent would not allow the en passant move capturing the checker pawn.
• Added clang tidy compiler flags in debug mode to disable all the optimisations. It now allows the use of some functions directly inside the debugger (like Bitboard.print()).
• Changed signature void generate_legal_moves(std::vector<Move>& moves, const Board& board, Color us) to inline void generate_legal_moves(std::vector<Move>& moves, const Board& board). This allows to pass the side to move as a board state member and avoids duplication and potential conflicts.

🧩 Type of Change

• 🐛 Bug fix
• ✨ New feature
• 📝 Documentation update
• ✅ Test addition or update
• 🔧 Build or CI/CD configuration