refactor(core): Enable Systemd and upgrade Sentinel service orchestration

The legacy crontabs have been superseded by Systemd to fortify orchestration of our global fleet of Sentinels.

While cron relies on timed, fire-and-forget execution, Systemd elevates our operations into natively integrated, state-aware OS daemons. This paradigm shift unlocks precise lifecycle management, unified logging (inspect all service logs with `journalctl -t ip-sentinel`), and absolute control over module deployment.

- Battle-Hardened: Sentinels now auto-resurrect upon failure, bypassing minute-long cron wait times.
- Zero-Impact Missions: Sentinels now operate under strict `idle` CPU/IO scheduling. This guarantees that automated maintenance cycles yield to high-priority user interactions, and never impact primary server workloads.
- Field Intelligence Auto-Stagger: Service-level `RandomizedDelaySec` natively staggers Agent check-ins to protect the Command Center.
- Legacy Fallback: OS interrogation on deployment ensures a seamless fallback to cron for Sentinels operating in Alpine/OpenRC environments.

The fleet is more resilient than ever, but the architecture is always evolving. I highly welcome any reviews/suggestions from the original Author/Commander to perfect this pull request!

master/uninstall_master.sh

@@ -34,19 +34,32 @@ if [[ ! "$CONFIRM_DEL" =~ ^[Yy]$ ]]; then
     exit 0
 fi
 
-# 1. 停止运行中的 Master 守护进程
-echo "[1/3] 正在终止后台中枢调度进程..."
+# 1. 停止并删除 Systemd 服务
+echo "[1/4] 正在停止并删除 Systemd 服务..."
+if command -v systemctl >/dev/null 2>&1; then
+    echo "[1/4] 💡 检测到 Systemd 环境，正在删除 Systemd 服务单元..."
+
+    systemctl disable --now ip-sentinel-master.service >/dev/null 2>&1
+    rm -f /etc/systemd/system/ip-sentinel-master.service
+    systemctl daemon-reload
+    systemctl reset-failed
+else
+    echo "[1/4] 💡 未检测到 Systemd，跳过此步骤..."
+fi
+
+# 2. 停止运行中的 Master 守护进程
+echo "[2/4] 正在终止后台中枢调度进程..."
 # [优化] 使用 pkill 替代 pgrep | xargs，指令更短、容错率更高
 pkill -9 -f "tg_master.sh" >/dev/null 2>&1 || true
 
-# 2. 清除看门狗定时任务 (Cron)
-echo "[2/3] 正在清理系统定时任务 (Cron)..."
+# 3. 清除看门狗定时任务 (Cron)
+echo "[3/4] 正在清理系统定时任务 (Cron)..."
 crontab -l 2>/dev/null | grep -v "tg_master.sh" > /tmp/cron_backup
 crontab /tmp/cron_backup
 rm -f /tmp/cron_backup
 
-# 3. 删除所有文件、配置与数据库
-echo "[3/3] 正在抹除核心程序、配置文件与 SQLite 数据库..."
+# 4. 删除所有文件、配置与数据库
+echo "[4/4] 正在抹除核心程序、配置文件与 SQLite 数据库..."
 if [ -d "$MASTER_DIR" ]; then
     rm -rf "$MASTER_DIR"
 fi