fix(mesh): use configured offline threshold in data store

- Add offline_threshold_hours parameter to MeshDataStore.__init__
- Compute is_online in _normalize_node using configured threshold
- Pass config.mesh_intelligence.offline_threshold_hours from main.py
- Removes reliance on health engine for initial is_online computation

Verification:
- Unit test confirms 2h threshold marks 3h-old node offline
- Unit test confirms 4h threshold marks same node online
- Container starts healthy with no config errors
- Health engine reports 16/16 infra online

meshai/main.py

@@ -265,6 +265,7 @@ class MeshAI:
             self.data_store = MeshDataStore(
                 source_configs=enabled_sources,
                 db_path="/data/mesh_history.db",
+                offline_threshold_hours=self.config.mesh_intelligence.offline_threshold_hours,
             )
             # Initial fetch and backfill
             self.data_store.force_refresh()
@@ -338,18 +339,18 @@ class MeshAI:
             )
             logger.info(f"Alert engine initialized (critical: {mi.critical_nodes}, channel: {mi.alert_channel})")
 
-
-        # Notification router
-        if self.config.notifications.enabled:
-            from .notifications.router import NotificationRouter
-            self.notification_router = NotificationRouter(
-                config=self.config.notifications,
-                connector=self.connector,
-                llm_backend=self.llm,
-                timezone=self.config.timezone,
-            )
-            logger.info("Notification router initialized")
-
+
+        # Notification router
+        if self.config.notifications.enabled:
+            from .notifications.router import NotificationRouter
+            self.notification_router = NotificationRouter(
+                config=self.config.notifications,
+                connector=self.connector,
+                llm_backend=self.llm,
+                timezone=self.config.timezone,
+            )
+            logger.info("Notification router initialized")
+
         # Environmental feeds
         env_cfg = self.config.environmental
         if env_cfg.enabled:
@@ -554,48 +555,48 @@ class MeshAI:
         if pid_file.exists():
             pid_file.unlink()
 
-    async def _dispatch_alerts(self, alerts: list[dict]) -> None:
-        """Dispatch alerts to subscribers and alert channel."""
-        mi = self.config.mesh_intelligence
-        alert_channel = getattr(mi, 'alert_channel', -1)
-
-        for alert in alerts:
-            message = alert["message"]
-            logger.info(f"ALERT: {message}")
-
-            # Route through notification router if enabled
-            if self.notification_router:
-                try:
-                    await self.notification_router.process_alert(alert)
-                except Exception as e:
-                    logger.error(f"Notification router error: {e}")
-
-            # Fallback: Send to alert channel if no notification router
-            elif alert_channel >= 0 and self.connector:
-                try:
-                    self.connector.send_message(
-                        text=message,
-                        destination=None,
-                        channel=alert_channel,
-                    )
-                    logger.info(f"Alert sent to channel {alert_channel}")
-                except Exception as e:
-                    logger.error(f"Failed to send channel alert: {e}")
-
-                # Fallback: Send DMs to matching subscribers
-                if self.alert_engine and self.subscription_manager:
-                    subscribers = self.alert_engine.get_subscribers_for_alert(alert)
-                    for sub in subscribers:
-                        user_id = sub["user_id"]
-                        try:
-                            await self._send_sub_dm(user_id, message)
-                            logger.info(f"Alert DM sent to {user_id}: {alert['type']}")
-                        except Exception as e:
-                            logger.error(f"Failed to send alert DM to {user_id}: {e}")
-
-        if self.alert_engine:
-            self.alert_engine.clear_pending()
-
+    async def _dispatch_alerts(self, alerts: list[dict]) -> None:
+        """Dispatch alerts to subscribers and alert channel."""
+        mi = self.config.mesh_intelligence
+        alert_channel = getattr(mi, 'alert_channel', -1)
+
+        for alert in alerts:
+            message = alert["message"]
+            logger.info(f"ALERT: {message}")
+
+            # Route through notification router if enabled
+            if self.notification_router:
+                try:
+                    await self.notification_router.process_alert(alert)
+                except Exception as e:
+                    logger.error(f"Notification router error: {e}")
+
+            # Fallback: Send to alert channel if no notification router
+            elif alert_channel >= 0 and self.connector:
+                try:
+                    self.connector.send_message(
+                        text=message,
+                        destination=None,
+                        channel=alert_channel,
+                    )
+                    logger.info(f"Alert sent to channel {alert_channel}")
+                except Exception as e:
+                    logger.error(f"Failed to send channel alert: {e}")
+
+                # Fallback: Send DMs to matching subscribers
+                if self.alert_engine and self.subscription_manager:
+                    subscribers = self.alert_engine.get_subscribers_for_alert(alert)
+                    for sub in subscribers:
+                        user_id = sub["user_id"]
+                        try:
+                            await self._send_sub_dm(user_id, message)
+                            logger.info(f"Alert DM sent to {user_id}: {alert['type']}")
+                        except Exception as e:
+                            logger.error(f"Failed to send alert DM to {user_id}: {e}")
+
+        if self.alert_engine:
+            self.alert_engine.clear_pending()
+
     async def _check_scheduled_subs(self) -> None:
         """Check for and deliver due scheduled reports."""
         from datetime import datetime