Add Arch Linux packaging, cross-compilation support, and binary generation

- Introduce Arch Linux package build process, supporting both x86_64 and aarch64 architectures.
- Add Arch-specific configuration files for service, sysusers, and tmpfiles to facilitate system integration.
- Update packaging script to dynamically handle Arch-specific builds and configure PKGBUILD fields.
- Add cross-compilation support, enabling building for ARM (aarch64) on x86_64 systems.
- Implement binary generation for both architectures, allowing separate or unified binary outputs.
- Include npm scripts to automate Arch build and cross-compilation processes.
- Simplify deployment and integration for Arch-based systems.

build/arch/audiobookshelf.service

@@ -0,0 +1,16 @@
+[Unit]
+Description=Self-hosted audiobook server for managing and playing audiobooks
+Requires=network.target
+
+[Service]
+Type=simple
+EnvironmentFile=/etc/conf.d/audiobookshelf
+WorkingDirectory=/var/lib/audiobookshelf
+ExecStart=/usr/bin/audiobookshelf
+ExecReload=/bin/kill -HUP $MAINPID
+Restart=always
+User=audiobookshelf
+Group=audiobookshelf
+
+[Install]
+WantedBy=multi-user.target