[US-05] Saving and restoring the game

Implementation Summary

This merge request implements comprehensive game save/load functionality for the Battleship game, addressing all acceptance criteria from Issue #5.

Key Features Implemented:

1. Game State Serialization (GameState.java)

   • Complete game state capture including players, boards, ships, shots, current turn, difficulty, and timing
   • Serializable implementation for file persistence
   • Running time calculation for game duration tracking

2. Save/Load Service (SaveLoadService.java)

   • Robust file operations with comprehensive error handling
   • Validation for corrupted, missing, and incompatible files
   • Directory creation support for custom file paths
   • File integrity checks and user-friendly error reporting

3. Game Service Integration (GameService.java)

   • Seamless integration with existing game logic
   • State preservation during save/load operations
   • Error recovery that preserves current game on failed loads

4. User Interface (Main.java)

   • Main menu with save/load options
   • File path selection for user flexibility
   • Clear error messages and status feedback

Acceptance Criteria Coverage:

✅ Criterion 1: "If the game is saved and loaded right away, every visible part and all internal values should be identical"

• Complete state preservation including player turns, board states, ship damage, and game timing
• Hidden information remains properly hidden after loading

✅ Criterion 2: "If a corrupted file is loaded, an error is displayed and the game remains the same"

• Comprehensive error handling for corrupted, missing, and incompatible files
• Current game state preserved on failed load attempts
• Clear error messages to the user

✅ Criterion 3: "If a completed game is saved and later loaded, it stays finished and waits for a new start"

• Finished game state properly serialized and restored
• Game completion status preserved across save/load cycles

Technical Implementation:

• Architecture: Follows layered MVC pattern as specified in ORCH_PLAN.json
• Serialization: Java Object Serialization for efficient state persistence
• Error Handling: Comprehensive exception handling with user-friendly messages
• File Operations: Support for user-selectable file locations and names
• State Management: Complete game state capture and restoration

Testing:

Comprehensive test suite created with:

• 25 test cases for SaveLoadService covering file operations and error scenarios
• 15 test cases for GameService integration testing
• Full coverage of all acceptance criteria
• Edge case testing for corrupted files and error conditions

Dependencies Verified:

• All prerequisite issues (#1-4) completed as per ORCH_PLAN.json dependency graph
• Implementation builds upon existing game infrastructure
• No breaking changes to existing functionality

Closes #5