shadowsocks/ShadowsocksX-NG ? reverse-engineered prompt

Build me a macOS app that works like a Shadowsocks client, with a clean Swift interface and a background proxy service that keeps running through launchd even after the app closes. I want it to let me add and manage server profiles, import them from a URL or from the clipboard, scan a QR code from the screen, and share a profile by QR code or link. It should support switching system proxy settings on and off, plus a manual mode where I can use the SOCKS5 proxy myself without changing system settings.

It should also support PAC mode, including updating the PAC list from GitHub, and let me add custom rules. Please include support for modern AEAD ciphers and the common SIP003 plugins like kcptun, simple obfs, and v2ray plugin. Keep it feeling like a real desktop app on macOS, not a command line tool. If you need current setup details, check the project docs online first.