fix(app, ios): adopt firebase-ios-sdk 12.9.0

see upstream release notes https://firebase.google.com/support/release-notes/ios#version_1290_-_february_3_2026

Author: mikehardy

docs/index.md

@@ -335,12 +335,12 @@ Open your projects `/ios/Podfile` and add any of the globals shown below to the
 
 ```ruby
 # Override Firebase SDK Version if desired
-$FirebaseSDKVersion = '12.8.0'
+$FirebaseSDKVersion = '12.9.0'
 ```
 
 Once changed, reinstall your projects pods via pod install and rebuild your project with `npx react-native run-ios`.
 
-Alternatively, if you cannot edit the Podfile easily (as when using Expo), you may add the environment variable `FIREBASE_SDK_VERSION=12.8.0` (or whatever version you need) to the command line that installs pods. For example `FIREBASE_SDK_VERSION=12.8.0 yarn expo prebuild --clean`
+Alternatively, if you cannot edit the Podfile easily (as when using Expo), you may add the environment variable `FIREBASE_SDK_VERSION=12.9.0` (or whatever version you need) to the command line that installs pods. For example `FIREBASE_SDK_VERSION=12.9.0 yarn expo prebuild --clean`
 
 ### Android Performance
 

packages/app/package.json

@@ -105,7 +105,7 @@
   },
   "sdkVersions": {
     "ios": {
-      "firebase": "12.8.0",
+      "firebase": "12.9.0",
       "iosTarget": "15.0",
       "macosTarget": "10.15",
       "tvosTarget": "15.0"