Add CONTRIBUTING.md with platform build instructions and formatting tools

[Copilot]

Added comprehensive contributor documentation covering build processes across platforms and code formatting requirements.

Changes

• CONTRIBUTING.md: New file with platform-specific build instructions (macOS, Windows, Ubuntu, Arch, Fedora, openSUSE, FlatHub) and formatting tool usage

  • clang-format-19 for C/C++ files: format and check commands
  • gersemi for CMake files: installation, format and check commands
  • Development workflow, coding standards (C17/C++17), PR process and checklist
  • Links to existing docs, community channels, and resources

• .gitignore: Added !CONTRIBUTING.md exception to allowlist pattern

Formatting Examples

# Format all C/C++ files
find src -name "*.c" -o -name "*.cpp" -o -name "*.h" -o -name "*.hpp" | xargs clang-format-19 -i

# Format all CMake files
gersemi -i CMakeLists.txt $(find cmake -name "*.cmake")

Original prompt

Create CONTRIBUTING.md. Include how to build on each platform and how to apply formatting tools.

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💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.