Offline UX: network failures show quiet 'offline, n queued' not errors; auto-sync on connectivity regain + 45s heartbeat

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/package-lock.json

@@ -10,6 +10,7 @@
       "dependencies": {
         "@expo/ui": "~57.0.9",
         "@react-native-async-storage/async-storage": "2.2.0",
+        "@react-native-community/netinfo": "12.0.1",
         "expo": "~57.0.11",
         "expo-constants": "~57.0.9",
         "expo-crypto": "~57.0.1",
@@ -2194,6 +2195,16 @@
         "react-native": "^0.0.0-0 || >=0.65 <1.0"
       }
     },
+    "node_modules/@react-native-community/netinfo": {
+      "version": "12.0.1",
+      "resolved": "https://registry.npmjs.org/@react-native-community/netinfo/-/netinfo-12.0.1.tgz",
+      "integrity": "sha512-P/3caXIvfYSJG8AWJVefukg+ZGRPs+M4Lp3pNJtgcTYoJxCjWrKQGNnCkj/Cz//zWa/avGed0i/wzm0T8vV2IQ==",
+      "license": "MIT",
+      "peerDependencies": {
+        "react": "*",
+        "react-native": ">=0.59"
+      }
+    },
     "node_modules/@react-native-masked-view/masked-view": {
       "version": "0.3.2",
       "resolved": "https://registry.npmjs.org/@react-native-masked-view/masked-view/-/masked-view-0.3.2.tgz",