deprecate the vertex ai quickstart app (#2700)

Developers should now refer to https://github.com/firebase/quickstart-android/tree/master/firebase-ai

Author: thatfiredev

copy_mock_google_services_json.sh

@@ -21,4 +21,3 @@ cp mock-google-services.json inappmessaging/app/google-services.json
 cp mock-google-services.json perf/app/google-services.json
 cp mock-google-services.json messaging/app/google-services.json
 cp mock-google-services.json storage/app/google-services.json
-cp mock-google-services.json vertexai/app/google-services.json

vertexai/README.md

@@ -1,30 +1,10 @@
-# Firebase Vertex AI Sample for Android (Kotlin)
-
-This Android sample app demonstrates how to use state-of-the-art
-generative AI models (like Gemini) to build AI-powered features and applications.
-
-To try out this sample app, you need to use latest stable version of Android Studio.
-However, if you want to latest lint checks and AI productivity features in Android
-Studio use the latest preview version of [Android Studio](https://developer.android.com/studio/preview).
-
-You can clone this repository or import the project from Android Studio following the steps
-[here](https://developer.android.com/jetpack/compose/setup#sample).
-
-## Screenshots
-
-<img src="screenshots/screenshots.png" alt="Screenshot">
-
-## Requirements
-
-TODO
-
-## Features
-
-This sample showcases the following API capablilites:
-* Generate Text - demonstrates the Text feature from the SDK
-* Photo Reasoning - demonstrates the MultiModal feature from the SDK
-* Chat - demonstrates the Multi-turn Conversations feature from the SDK
-
-## Documentation
-
-TODO
+# [DEPRECATED] Firebase Vertex AI Sample for Android (Kotlin)
+
+> [!CAUTION] 
+> On May 20, 2025, we released the Firebase AI SDK (`firebase-ai`). This SDK replaces the previous Vertex AI in Firebase SDK (`firebase-vertexai`) to accommodate the evolving set of supported features and services.
+> * The new Firebase AI SDK provides Preview support for the Gemini Developer API, including its free tier offering.
+> * Using the Firebase AI SDK with the Vertex AI Gemini API is still generally available (GA).
+>
+> If you're using the old `firebase-vertexai`, we recommend [migrating to firebase-ai](https://firebase.google.com/docs/ai-logic/migrate-to-latest-sdk) because all new development and features will be in this new SDK.
+>
+> The quickstart sample app for `firebase-ai` can be found in the [/firebase-ai directory](../firebase-ai/).