feat(mobile): replace Sentry with Firebase Crashlytics

Migrate error tracking from Sentry to Firebase Crashlytics.
Bump version to 1.0.4, add Discord notification triggers.

apps/mobile/package.json

@@ -24,11 +24,11 @@
     "@react-native-async-storage/async-storage": "1.23.1",
     "@react-native-firebase/analytics": "^23.8.2",
     "@react-native-firebase/app": "^23.8.2",
+    "@react-native-firebase/crashlytics": "^23.8.4",
     "@react-native-google-signin/google-signin": "^16.1.1",
     "@react-navigation/bottom-tabs": "^7.0.0",
     "@react-navigation/native": "^7.0.0",
     "@react-navigation/native-stack": "^7.0.0",
-    "@sentry/react-native": "~6.10.0",
     "@supabase/supabase-js": "^2.39.0",
     "@tanstack/react-query": "^5.17.0",
     "babel-preset-expo": "~12.0.0",