Add CLAUDE.md codebase guide for AI assistants

[dawc17]

Summary

This PR adds a comprehensive CLAUDE.md file that serves as a detailed guide for AI assistants working in the VoxelEngine repository. The document provides essential context about the project structure, architecture, build system, and development conventions.

Key Changes

• Project Overview: Documents VoxelEngine as a ~115k line C++17 Minecraft-style voxel game with procedural terrain, multi-threaded chunk streaming, and OpenGL 4.6 rendering
• Build System Guide: Explains CMake configuration, build commands for Linux/Windows, and asset embedding pipeline using xxd
• Directory Structure: Maps out the complete project layout including src/, assets/, libs/, and cmake/ directories
• Architecture Documentation: Details initialization flow, key subsystems (Renderer, ChunkManager, JobSystem, RegionManager, etc.), and global state management patterns
• Chunk & Block Systems: Explains chunk coordinates, storage format, region file structure, and the block type registry system
• Rendering Pipeline: Documents shader organization, vertex format, texture array packing, and greedy meshing algorithm
• Threading Model: Clarifies the job system's async processing and main-thread-only OpenGL constraint
• Code Conventions: Establishes naming standards (PascalCase classes, camelCase functions, g_ prefix for globals), file layout, and style guidelines
• Feature Addition Checklists: Provides step-by-step guides for adding new blocks, audio events, shaders, world features, and UI screens
• Performance & Pitfalls: Highlights critical constraints (frustum culling, greedy meshing, chunk radius limits) and common mistakes (thread safety, coordinate confusion, asset embedding)

Implementation Details

The guide is structured as a reference document with:

• Clear section headers and subsections for easy navigation
• Code examples showing actual patterns used in the codebase
• Tables summarizing systems, shaders, commands, and naming conventions
• Practical checklists for common development tasks
• Explicit warnings about threading, coordinate systems, and asset handling

This document serves as a bridge between the codebase and AI assistants, reducing context-gathering time and establishing consistent development practices.

https://claude.ai/code/session_01HypWGGXnZ7R8gCzpt7o2yH