feat: UI/CLI 配置代理账密；armv7 仅保留整包

- 面板可设置 7890 账号密码（管理 API :9091）
- cpxy auth --user/--pass/--clear/--show
- Release armv7 整包已验证，已删除分片资产

systemd/cellular-proxy-admin.service

@@ -0,0 +1,24 @@
+[Unit]
+Description=cellular-proxy admin API (proxy auth config)
+After=network-online.target cellular-proxy.service
+Wants=network-online.target
+
+[Service]
+Type=simple
+Environment=INSTALL_DIR=@INSTALL_DIR@
+Environment=CPXY_SETTINGS=@INSTALL_DIR@/etc/settings.conf
+Environment=CPXY_APPLY_AUTH=@INSTALL_DIR@/scripts/apply-proxy-auth.sh
+Environment=ADMIN_LISTEN_HOST=0.0.0.0
+Environment=ADMIN_LISTEN_PORT=9091
+ExecStart=/usr/bin/python3 @INSTALL_DIR@/scripts/admin-api.py
+Restart=on-failure
+RestartSec=2
+NoNewPrivileges=true
+ProtectSystem=full
+ProtectHome=true
+PrivateTmp=true
+ReadWritePaths=@INSTALL_DIR@ /var/lib/cellular-proxy /var/log/cellular-proxy
+User=root
+
+[Install]
+WantedBy=multi-user.target