优化 Debian 包管理，简化发行版配置

- CI：简化 Debian 包发布流程，统一使用 stable 发行版
- 移除 bookworm 和 trixie 多发行版支持，简化维护
- postinst：优化安装完成提示，提供清晰的配置和启动步骤
- postrm/prerm：改进卸载和升级前的清理逻辑
- README：更新安装说明，使用 stable 仓库
- install.deb.sh：同步更新仓库配置

debian/prerm

@@ -4,11 +4,13 @@ set -e
 # Stop services before removal
 if [ -d /run/systemd/system ]; then
     for service in xxxigcc-server.service xxxigcc-daemon.service; do
-        if systemctl is-active "$service" >/dev/null 2>&1; then
+        if systemctl is-active --quiet "$service"; then
+            echo "Stopping $service..."
             systemctl stop "$service"
         fi
 
-        if systemctl is-enabled "$service" >/dev/null 2>&1; then
+        if systemctl is-enabled --quiet "$service"; then
+            echo "Disabling $service..."
             systemctl disable "$service"
         fi
     done