Develop - AppFunctions for Gemini and wallpaper color extraction before apply

[sameerasw]

This pull request introduces support for the Android AppFunctions API (Android 14+, API 36+) to the Essentials app, enabling system-level automation and device control through a new AppFunctionService. It adds a comprehensive set of AppFunctions for device actions, automations, and status queries, with all necessary service declarations, DTOs, and integration points. ProGuard rules and dependencies are updated accordingly.

AppFunctions Integration and Service Implementation

• Added the new EssentialsAppFunctionService and abstract base class BaseEssentialsAppFunctionService implementing a wide range of AppFunctions for device control (flashlight, sound mode, battery saver, AOD, notification lighting, freeze tags, automations, etc.), with detailed KDoc documentation for each function.
• Registered the service in AndroidManifest.xml with required permissions, schema, and metadata properties for AppFunctions.
• Introduced AppFunctionAvailabilityManager to update AppFunction availability on supported devices, invoked during app initialization in EssentialsApp. [1] [2]

Data Transfer Objects (DTOs) for AppFunctions

• Added serializable DTOs for AppFunction communication: AppFunctionResult, AutomationSummary, CreateAutomationParams, and others to support function parameters and responses. [1] [2] [3]

Build and ProGuard Configuration

• Updated build.gradle.kts to include androidx.appfunctions dependencies and KSP compiler.
• Updated proguard-rules.pro to keep new AppFunctions and related classes for correct operation in release builds.