fix(mobile): fix EAS build failure — expo doctor schema/version errors

Build #4 failed at the expo doctor pre-build check EAS runs, with two
real issues:

- app.json's newArchEnabled key is no longer a valid Expo config field
  in SDK 57 (New Architecture is the only architecture now, so the
  opt-in toggle was removed) — the schema validator rejected it as an
  unknown property.
- expo-router was pinned to 5.1.11, an old-style version number
  predating Expo's SDK-aligned versioning — way behind the ~57.0.19
  expected for this SDK. expo-linking/expo-secure-store were a patch
  version behind too. Fixed via `npx expo install --fix` rather than
  guessing version numbers.

The expo-router bump changed tabBarIcon's expected color prop type
from `string` to RN's `ColorValue`; updated NotificationsTabIcon's
signature to match.

`npx expo-doctor` now reports 18/18 checks passed.

mobile/app.json

@@ -7,7 +7,6 @@
     "orientation": "portrait",
     "icon": "./assets/icon.png",
     "userInterfaceStyle": "automatic",
-    "newArchEnabled": true,
     "ios": {
       "supportsTablet": true,
       "bundleIdentifier": "org.pawfeed.app"

mobile/app/(app)/(tabs)/_layout.tsx

@@ -1,5 +1,5 @@
 import { useMemo } from "react";
-import { View, Text, Pressable, StyleSheet } from "react-native";
+import { View, Text, Pressable, StyleSheet, type ColorValue } from "react-native";
 import { Tabs, useRouter } from "expo-router";
 import { useTranslation } from "react-i18next";
 import { useQuery } from "@tanstack/react-query";
@@ -137,7 +137,7 @@ function MessagesHeaderButton() {
   );
 }
 
-function NotificationsTabIcon({ color, size }: { color: string; size: number }) {
+function NotificationsTabIcon({ color, size }: { color: ColorValue; size: number }) {
   const trpc = useTRPC();
   const { activePetId } = useActivePet();
   const { colors } = useTheme();

mobile/package.json

@@ -10,18 +10,18 @@
     "@tanstack/react-query-persist-client": "^5.102.8",
     "@trpc/client": "11.17.0",
     "@trpc/tanstack-react-query": "11.17.0",
-    "expo": "~57.0.18",
+    "expo": "~57.0.20",
     "expo-constants": "~57.0.16",
     "expo-dev-client": "~57.0.18",
     "expo-file-system": "~57.0.6",
     "expo-font": "~57.0.3",
     "expo-image": "~57.0.4",
     "expo-image-picker": "~57.0.16",
-    "expo-linking": "~57.0.8",
+    "expo-linking": "~57.0.9",
     "expo-localization": "~57.0.1",
     "expo-notifications": "~57.0.17",
-    "expo-router": "^5.1.11",
-    "expo-secure-store": "~57.0.2",
+    "expo-router": "~57.0.19",
+    "expo-secure-store": "~57.0.3",
     "expo-status-bar": "~57.0.1",
     "expo-system-ui": "~57.0.3",
     "expo-video": "~57.0.3",