feat(release): add arm64 builds for macOS and Windows

[dronenb]

This PR adds support for:

• Building guard for ARM64 macOS
• Building guard for ARM64 Windows

It also:

• Fixes Makefile on macOS due to BSD date incompatibility with GNU date
• Adds some build directories to .gitignore

Fixes #438

This was tested by running:

make all-build COMPRESS=yes

and then checking what the bin/ directory contains:

file bin/guard-*

Yielding:

bin/guard-darwin-amd64:        Mach-O 64-bit executable x86_64
bin/guard-darwin-amd64.tar.gz: gzip compressed data, last modified: Wed Feb 18 01:08:46 2026, from Unix, original size modulo 2^32 64530432
bin/guard-darwin-arm64:        Mach-O 64-bit executable arm64
bin/guard-darwin-arm64.tar.gz: gzip compressed data, last modified: Wed Feb 18 01:08:55 2026, from Unix, original size modulo 2^32 61780480
bin/guard-linux-amd64:         ELF 64-bit LSB executable, x86-64, version 1 (SYSV), statically linked, BuildID[sha1]=f4967e0e22504b8ad10cbfa528967785a5cf9ea6, with debug_info, not stripped
bin/guard-linux-amd64.tar.gz:  gzip compressed data, last modified: Wed Feb 18 01:07:39 2026, from Unix, original size modulo 2^32 62567424
bin/guard-linux-arm:           ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV), statically linked, BuildID[sha1]=25545e44ef21823396a1931a1195f79a358b564f, with debug_info, not stripped
bin/guard-linux-arm.tar.gz:    gzip compressed data, last modified: Wed Feb 18 01:07:47 2026, from Unix, original size modulo 2^32 59786240
bin/guard-linux-arm64:         ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, BuildID[sha1]=9071d269c6a5ad5fd179fcc2320581846c185ea8, with debug_info, not stripped
bin/guard-linux-arm64.tar.gz:  gzip compressed data, last modified: Wed Feb 18 01:07:56 2026, from Unix, original size modulo 2^32 59410432
bin/guard-windows-amd64.exe:   PE32+ executable (console) x86-64, for MS Windows
bin/guard-windows-amd64.zip:   Zip archive data, at least v2.0 to extract, compression method=deflate
bin/guard-windows-arm64.exe:   PE32+ executable (console) Aarch64, for MS Windows
bin/guard-windows-arm64.zip:   Zip archive data, at least v2.0 to extract, compression method=deflate