feat(watch): treat ModemManager journal as redial standard

Use MM registration/packet-service events as the recovery trigger
instead of public egress probes, so re-register heals with zero
cellular traffic. Wait for wwan IPv4 after settle, coalesce bursts,
and keep ip-monitor + poll as fallbacks.

config/settings.conf.example

@@ -29,8 +29,19 @@ REQUIRE_CELLULAR_IFACE=true
 CELLULAR_IFACE_PATTERNS=wwan,wwp,usb,enx,ppp,cdc
 # 后台监控（推荐开）：网卡改名/掉线/无 IPv4 时自动 rebind；默认开启 long-running watch
 ENABLE_CELLULAR_WATCH=true
-# watch 轮询兜底间隔秒（事件驱动 ip monitor 为主）
+# watch 轮询兜底间隔秒（事件驱动 ip monitor + ModemManager 日志为主）
 WATCH_INTERVAL_SEC=60
+# 以 ModemManager 日志为「重拨/重注册」标准（零公网流量，只读本机 journal）
+# 命中 home→searching / attached→detached / bearer 断连等后：settle → 等 IPv4 → generate/restart
+WATCH_MM_EVENTS=true
+WATCH_MM_UNIT=ModemManager
+# 事件后先等几秒再查数据面（避免刚 detached 就 generate）
+WATCH_MM_SETTLE_SEC=5
+# 等待 wwan IPv4 / MM home 的最长时间
+WATCH_MM_READY_TIMEOUT_SEC=90
+WATCH_MM_READY_POLL_SEC=2
+# 同一轮抖动合并窗口（searching→registering→home 只恢复一次）
+WATCH_MM_COALESCE_SEC=20
 
 # ---- 代理监听（局域网其它设备用 0.0.0.0）----
 # mixed = 同一端口同时支持 HTTP 代理 与 SOCKS5