feat: offline SMS fallback for important notifications

断网时把验证码、来电用短信发到 iPhone：
- ConnectivityMonitor: NetworkCallback 监听在线状态
- CarrierDetector: SIM MCC+MNC 映射移动/联通/电信/广电
- CarrierBalanceQuery: 发免费查询短信拿套餐短信余量，解析回执
- SmsFallbackForwarder: 限频(5min)/余额(≤5挂起)/紧要性检查
- NotificationProcessor 拦截运营商回执(10086/10010/10001/10099)
- 设置页新增短信兜底卡片，首页余额耗尽警告

版本 1.3.0 → 1.4.0

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/src/main/java/com/a2i/forwarder/service/NotifyListenerService.kt

@@ -44,6 +44,17 @@ class NotifyListenerService : NotificationListenerService() {
             return
         }
 
+        // ---- 断网兜底：离线时紧要通知走短信，其余不转发避免离线堆积 ----
+        val online = app.connectivityMonitor.isOnline.value
+        if (!online) {
+            if (app.smsForwarder.isSmsWorthy(d)) {
+                app.smsForwarder.forward(d)
+            } else {
+                app.logStore.addLog(ForwardLog(now, sbn.packageName, d.appLabel, msg.title, msg.body, "filtered", "离线非紧要通知"))
+            }
+            return
+        }
+
         val server = app.settings.currentServer.value
         if (server == null || server.deviceKey.isBlank()) {
             app.logStore.addLog(ForwardLog(now, sbn.packageName, d.appLabel, msg.title, msg.body, "failed", "未配置 Bark key"))