Implement JASC palette save/load and core tileset I/O infrastructure

[grunt-lucas]

Summary

This PR implements fundamental save and load functionality for Porytiles2 tilesets, focusing on JASC palette format support and core I/O infrastructure.

Key Features Added

JASC Palette Support:

• Complete JASC-PAL (Paintshop Pro) file format implementation
• JascPalLoader with full validation and error handling
• JascPalSaver with proper CRLF line endings
• Robust parsing with detailed error messages for malformed files

Core I/O Infrastructure:

• File-agnostic FilePalLoader/FilePalSaver interfaces for extensibility
• Enhanced PorymapTilesetComponent with array-based palette storage (16 palettes)
• Complete tileset save/load pipeline in TilesetRepo
• Binary file I/O for metatiles.bin and metatile_attributes.bin
• PNG tiles loading and saving integration

Error Handling & Robustness:

• Comprehensive error propagation throughout the I/O stack
• Detailed error messages with file paths and context
• Graceful handling of missing optional artifacts
• Input validation with bounds checking

Code Quality Improvements:

• New string_utils.hpp template header with parsing utilities
• Fixed include path inconsistencies across the codebase
• Corrected error messages in legacy Porytiles1 code
• Added NoopArtifactChecksumProvider for testing

Technical Details

Architecture Changes:

• PorymapTilesetComponent now uses std::array<RgbaPal, 16> instead of std::vector
• Added indexed palette access methods (set_pal(), pal_at()) with bounds checking
• Extended ProjectTilesetArtifactReader/Writer with palette I/O capabilities

File Format Support:

• JASC-PAL format with "JASC-PAL", "0100", size declaration parsing
• Space-separated RGB values (0-255 range) with validation
• Binary metatile data packed as 16-bit values with tile index, flip flags, and palette index
• Placeholder metatile attributes (TODO: implement full attribute handling)

Integration Points:

• Debug command now demonstrates full save/load cycle
• Configurable greyscale palette for tiles.png export
• Error handling integration with fmt library formatting

Files Changed

• 35 files modified with 734 additions and 133 deletions
• New infrastructure files: JASC loaders/savers, string utilities, checksum provider
• Enhanced domain model with robust palette management
• Improved error handling across repository layer

Testing & Validation

The debug command provides end-to-end testing of the save/load pipeline, enabling validation of:

• JASC palette file round-trip integrity
• Binary artifact generation and parsing
• Error handling for malformed input files
• Integration between all I/O components

This foundational work enables future development of the complete tileset compilation pipeline while maintaining clean architecture and comprehensive error handling.