Explore PE header-based architecture detection for pack command

Summary

The current architecture mismatch detection in the pack command uses folder path RID segments (e.g., win-x64, win-arm64) as a heuristic. A more authoritative approach would be to read the PE header (IMAGE_FILE_HEADER.Machine field) of the .exe in the build output folder.

Background

Three possible sources for determining build output architecture were evaluated:

The manifest's ProcessorArchitecture attribute is optional and defaults to "neutral", making it unreliable as a sole source. The PE header is the most reliable option since the .exe is always present and unambiguously declares its target architecture.

Proposal

• Read the first .exe found in the selected build output folder
• Parse the PE header at the fixed offset to read IMAGE_FILE_HEADER.Machine
• Map machine constants to architecture strings:
  • 0x8664 → x64
  • 0xAA64 → arm64
  • 0x014C → x86
• Use this as the primary detection method, with path-based as fallback

Considerations

• Requires binary file I/O (reading ~64 bytes from the .exe)
• Need to handle the case where multiple .exe files exist in the folder
• Should gracefully fall back to path detection if PE parsing fails

Related

• PR #93 introduced the current path-based detection
• Issue #81 tracks ancestor-path false positive edge cases (which PE detection would also resolve)

Read the current path-based architecture detection in the pack command, introduced by PR #93, and review issue #81 for related edge cases. Done means the selected output folder's first .exe is checked for x64, arm64, or x86 via its PE Machine value, with path detection as a fallback and multiple-executable behavior addressed.