Native Windows support

[mekwall]

This pull request introduces significant changes to add native Windows compatibility to the project while maintaining support for other platforms. The changes include updates to the build system, platform-specific handling in the codebase, and various compatibility adjustments for Windows. Below is a categorized summary of the most important changes:

Build System Updates

• Added support for Windows in the GitHub Actions workflow (.github/workflows/cmake.yml). This includes adding a Windows runner and modifying the CMake configuration, build, and test steps to handle Windows-specific paths and commands.

Platform-Specific Code Adjustments

• Updated CXXSniffer.cmake to use appropriate compiler flags for Windows (/W4) and other platforms (-Wall -Wextra).
• Modified Datetime::timegm in src/Datetime.cpp to handle timezone environment variables differently on Windows using _putenv_s and _tzset. [1] [2]

Windows-Specific Implementations in FS.cpp

• Introduced platform-specific headers and macros in src/FS.cpp to handle file system operations like directory creation, file locking, and path expansion on Windows. [1] [2]
• Replaced POSIX-specific functions (e.g., realpath, access, unlink) with Windows equivalents (e.g., GetFullPathNameA, _access, _unlink) where applicable. [1] [2] [3]
• Implemented Windows-specific logic for directory listing, recursive removal, and globbing using FindFirstFileA and FindNextFileA. [1] [2] [3]

File and Directory Operations

• Added Windows-compatible alternatives for file and directory operations such as mkdir, rmdir, chdir, and file truncation using _mkdir, _rmdir, _chdir, and _chsize. [1] [2] [3]
• Adjusted file synchronization logic to use FlushFileBuffers on Windows instead of fsync or fdatasync.

Minor Fixes

• Replaced logical operators and with && in src/PEG.cpp as MSVC doesn't recognize them when using Windows headers.

[Copilot]

Pull Request Overview

This PR adds Windows compatibility across the build system, filesystem utilities, and environment handling so the project can build and run on both Windows and Unix-like platforms.

• Updated GitHub Actions and CMake to detect and configure MSVC/Windows builds
• Introduced #ifdef _WIN32 branches for POSIX APIs in filesystem and shared logic
• Added Windows-specific headers, typedefs, and WinAPI calls for file, directory, and time functions

Reviewed Changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/shared.cpp	Wrapped POSIX includes and execute() with Windows stubs
src/format.cpp	Guarded strings.h include under _WIN32
src/Table.cpp	Added Windows headers and _isatty logic
src/FS.h	Introduced windows.h include and mode_t typedef
src/FS.cpp	Implemented Windows fallbacks for access, mkdir, etc.
src/Datetime.cpp	Switched to _putenv_s/_tzset for timegm on Windows
cmake/CXXSniffer.cmake	Set /W4 flags when MSVC is detected
.github/workflows/cmake.yml	Added windows-latest runner and ctest invocation

Comments suppressed due to low confidence (1)

.github/workflows/cmake.yml:41

• On Windows runners the default shell is PowerShell, so this Bash-style if may not execute. Use ${{ runner.os }} expressions or a PowerShell step for Windows-specific logic.

          if [ "$RUNNER_OS" = "Windows" ]; then