feat(ai-logic): add samples demonstrating Gemini 3.1 Flash-Lite preview (firebase#2769)

This should add a new translation sample that uses Gemini 3.1 Flash-Lite preview

Also updates the audio summarization sample to use Gemini 3.1 Flash-Lite instead of Gemini 2.5 Flash.

Author: thatfiredev

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/feature/text/AudioSummarizationViewModel.kt

@@ -28,7 +28,7 @@ class AudioSummarizationViewModel : ChatViewModel() {
         val generativeModel = Firebase.ai(
             backend = GenerativeBackend.googleAI()
         ).generativeModel(
-            modelName = "gemini-2.5-flash"
+            modelName = "gemini-3.1-flash-lite-preview"
         )
         chat = generativeModel.startChat(
             listOf(

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/feature/text/TranslationViewModel.kt

@@ -0,0 +1,44 @@
+package com.google.firebase.quickstart.ai.feature.text
+
+import com.google.firebase.Firebase
+import com.google.firebase.ai.Chat
+import com.google.firebase.ai.ai
+import com.google.firebase.ai.type.Content
+import com.google.firebase.ai.type.GenerativeBackend
+import com.google.firebase.ai.type.content
+import com.google.firebase.quickstart.ai.ui.UiChatMessage
+import kotlinx.serialization.Serializable
+
+@Serializable
+object TranslationRoute
+
+class TranslationViewModel : ChatViewModel() {
+    override val initialPrompt: String
+        get() = """
+            Translate the following text to Spanish:
+            Hey, are you down to grab some pizza later? I'm starving!
+        """.trimIndent()
+
+    private val chat: Chat
+
+    init {
+        val generativeModel = Firebase.ai(
+            backend = GenerativeBackend.googleAI()
+        ).generativeModel(
+            modelName = "gemini-3.1-flash-lite-preview",
+            systemInstruction = content {
+                text("Only output the translated text")
+            }
+        )
+
+        chat = generativeModel.startChat()
+    }
+
+    override suspend fun performSendMessage(
+        prompt: Content,
+        currentMessages: List<UiChatMessage>
+    ) {
+        val response = chat.sendMessage(prompt)
+        validateAndDisplayResponse(response, currentMessages)
+    }
+}

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/ui/navigation/FirebaseAISamples.kt

@@ -36,6 +36,8 @@ import com.google.firebase.quickstart.ai.feature.text.SvgRoute
 import com.google.firebase.quickstart.ai.feature.text.SvgViewModel
 import com.google.firebase.quickstart.ai.feature.text.ThinkingChatRoute
 import com.google.firebase.quickstart.ai.feature.text.ThinkingChatViewModel
+import com.google.firebase.quickstart.ai.feature.text.TranslationRoute
+import com.google.firebase.quickstart.ai.feature.text.TranslationViewModel
 import com.google.firebase.quickstart.ai.feature.text.TravelTipsRoute
 import com.google.firebase.quickstart.ai.feature.text.TravelTipsViewModel
 import com.google.firebase.quickstart.ai.feature.text.VideoHashtagGeneratorRoute
@@ -46,6 +48,14 @@ import com.google.firebase.quickstart.ai.feature.text.WeatherChatRoute
 import com.google.firebase.quickstart.ai.feature.text.WeatherChatViewModel
 
 val FIREBASE_AI_SAMPLES = listOf(
+    Sample(
+        title = "Translate text",
+        description = "Use Gemini 3.1 Flash-Lite to translate text",
+        route = TranslationRoute,
+        screenType = ScreenType.CHAT,
+        viewModelClass = TranslationViewModel::class,
+        categories = listOf(Category.TEXT)
+    ),
     Sample(
         title = "Travel tips",
         description = "The user wants the model to help a new traveler" +
@@ -65,7 +75,7 @@ val FIREBASE_AI_SAMPLES = listOf(
     ),
     Sample(
         title = "Audio Summarization",
-        description = "Summarize an audio file",
+        description = "Use Gemini 3.1 Flash Lite to summarize an audio file",
         route = AudioSummarizationRoute,
         screenType = ScreenType.CHAT,
         viewModelClass = AudioSummarizationViewModel::class,
@@ -194,7 +204,7 @@ val FIREBASE_AI_SAMPLES = listOf(
         route = GoogleSearchGroundingRoute,
         screenType = ScreenType.CHAT,
         viewModelClass = GoogleSearchGroundingViewModel::class,
-        categories = listOf(Category.TEXT, Category.DOCUMENT)
+        categories = listOf(Category.TEXT)
     ),
     Sample(
         title = "Server Prompt Template - Imagen",