[Feature] Android/Compose skill for AI Agents/coding assistants

> [!NOTE]
> Feature requests are accepted only if the proposed skill fills a verified gap in state-of-the-art LLMs. To assess this, please test your use case against both a fast model (e.g., Gemini 3 Flash) and a reasoning/thinking model (e.g., Gemini 3.1 Pro).

### What is the gap in the LLM's knowledge?

It would be nice to have something similar to https://github.com/twostraws/swiftui-agent-skill, which is a SwiftUI based skill.

### Proposed Skill

The skill would cover best practices in modern Android development, i.e., using Jetpack Compose, Coroutines, Navigation 3, Flow effectively.

It should follow these guides:
- https://kotlinlang.org/docs/coding-conventions.html
- https://developer.android.com/kotlin/style-guide
- https://github.com/androidx/androidx/blob/androidx-main/compose/docs/compose-component-api-guidelines.md
- https://github.com/androidx/androidx/blob/androidx-main/compose/docs/compose-api-guidelines.md

The skill itself should be short and should point to different markdown files containing best practices

### Additional Context

Start by testing the Android development use case with Gemini 3 Flash and Gemini 3.1 Pro, then compare the gap with the linked SwiftUI agent skill. Read the Kotlin coding conventions, Android Kotlin style guide, and Compose component and API guidelines before designing the short skill and its supporting Markdown files. Done means the listed Compose, Coroutines, Navigation 3, and Flow practices are covered and the verified gap is documented.

Written by the indexing model from the issue text.