fix: Windows cross-compilation support (GOOS=windows)
- debugcli.go/debugtui.go: add //go:build !windows tag
- debugcli_windows.go/debugtui_windows.go: no-op stubs
- cdx/cdx.go: extract mmap to platform-specific files
- cdx/mmap_posix.go: syscall.Mmap/Munmap
- cdx/mmap_windows.go: no-op (falls back to read)
- ntx/ntx.go, ntx/build.go: same mmap extraction
- ntx/mmap_posix.go, ntx/mmap_windows.go: platform split
Builds verified: linux/amd64, windows/amd64, darwin/arm64, darwin/amd64
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Charles KWON OhJun
ad544a5528