refactor(ui): modularize mobile presentation into ui/mobile package

- Extract mobile screen composables into ui/mobile/ (MobileAgentDemoContent, MobileDebuggingContent, MobileSettingsContent, MobileConnectedAppsContent).
- Update top-level screen files (AgentDemoScreen, DebuggingScreen, SettingsScreen, ConnectedAppsScreen) to delegate UI rendering to ScreenLayoutFactory.
- Zero visual changes (100% parity with existing mobile UX).

Author: Paul Lammertsma

agent/app/src/main/java/com/example/appfunctions/agent/data/DataStoreSettingsRepository.kt

@@ -17,6 +17,7 @@ package com.example.appfunctions.agent.data
 
 import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences
+import androidx.datastore.preferences.core.booleanPreferencesKey
 import androidx.datastore.preferences.core.edit
 import androidx.datastore.preferences.core.stringPreferencesKey
 import androidx.datastore.preferences.core.stringSetPreferencesKey
@@ -39,6 +40,7 @@ class DataStoreSettingsRepository
             val SERVICE_TIER = stringPreferencesKey("service_tier")
             val PINNED_APPS = stringSetPreferencesKey("pinned_apps")
             val DISCONNECTED_APPS = stringSetPreferencesKey("disconnected_apps")
+            val APP_FUNCTION_DEBUGGING = booleanPreferencesKey("app_function_debugging")
         }
 
         override val geminiApiKey: Flow<String?> =
@@ -73,6 +75,11 @@ class DataStoreSettingsRepository
                 preferences[PreferencesKeys.DISCONNECTED_APPS] ?: emptySet()
             }
 
+        override val appFunctionDebuggingEnabled: Flow<Boolean> =
+            dataStore.data.map { preferences ->
+                preferences[PreferencesKeys.APP_FUNCTION_DEBUGGING] ?: true
+            }
+
         override suspend fun setGeminiApiKey(apiKey: String) {
             dataStore.edit { preferences -> preferences[PreferencesKeys.GEMINI_API_KEY] = apiKey }
         }
@@ -118,4 +125,10 @@ class DataStoreSettingsRepository
                 preferences[PreferencesKeys.DISCONNECTED_APPS] = newDisconnected
             }
         }
+
+        override suspend fun setAppFunctionDebuggingEnabled(enabled: Boolean) {
+            dataStore.edit { preferences ->
+                preferences[PreferencesKeys.APP_FUNCTION_DEBUGGING] = enabled
+            }
+        }
     }

agent/app/src/main/java/com/example/appfunctions/agent/data/SettingsRepository.kt

@@ -54,4 +54,10 @@ interface SettingsRepository {
         packageName: String,
         connected: Boolean,
     )
+
+    /** Flow of AppFunction debugging setting. */
+    val appFunctionDebuggingEnabled: Flow<Boolean>
+
+    /** Sets whether AppFunction debugging is enabled. */
+    suspend fun setAppFunctionDebuggingEnabled(enabled: Boolean)
 }

agent/app/src/main/java/com/example/appfunctions/agent/ui/layout/ScreenLayoutFactory.kt

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2026 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.example.appfunctions.agent.ui.layout
+
+import com.example.appfunctions.agent.ui.contracts.AgentDemoScreenLayout
+import com.example.appfunctions.agent.ui.contracts.ConnectedAppsScreenLayout
+import com.example.appfunctions.agent.ui.contracts.DebuggingScreenLayout
+import com.example.appfunctions.agent.ui.contracts.SettingsScreenLayout
+import com.example.appfunctions.agent.ui.mobile.agentdemo.MobileAgentDemoLayout
+import com.example.appfunctions.agent.ui.mobile.agentdemo.MobileConnectedAppsLayout
+import com.example.appfunctions.agent.ui.mobile.agentdemo.MobileSettingsLayout
+import com.example.appfunctions.agent.ui.mobile.debugging.MobileDebuggingLayout
+
+/**
+ * Centralized layout factory that resolves screen layout contracts for specific form factors.
+ * This pattern decouples screen routers from explicit form factor resolution conditionals,
+ * allowing new device form factors (e.g., Wear OS, Android XR, Auto) to be added cleanly.
+ */
+fun FormFactor.resolveAgentDemoLayout(): AgentDemoScreenLayout = MobileAgentDemoLayout
+
+fun FormFactor.resolveConnectedAppsLayout(): ConnectedAppsScreenLayout = MobileConnectedAppsLayout
+
+fun FormFactor.resolveSettingsLayout(): SettingsScreenLayout = MobileSettingsLayout
+
+fun FormFactor.resolveDebuggingLayout(): DebuggingScreenLayout = MobileDebuggingLayout