Proposal: Android-Specific Metadata Support in Recipes

Introduce support in python-for-android to parse Android-specific metadata from pyproject.toml of pip-installed packages. This enables modular bundling of assets into APK builds, allowing packages to contribute platform-native components directly.

## Example pyproject.toml Layout

```toml
[tool.python-for-android.android]
src = "android/src/"
res = "android/res/"
extra_manifest_xml = "android/extra_manifest.xml"
extra_manifest_application_xml= "android/extra_manifest_application.xml"
activities = [
{
"name": "org.package.android.MyActivity",
"process": ":package_process",
}
]
proguard = "android/proguard-rules.txt"
jniLibs = "android/jni/"
assets = "android/assets/"
resources = "android/resources"

etc. Etc.
```

## How It Works

- During dependency resolution (p4a.recipe or pip stage), check for [tool.python-for-android.android] in pyproject.toml.
- Resolve declared paths from the site-packages directory.
- Inject collected files into dists//build/ before Gradle build.

Please consider this.

THANKS!!

Start by reading the dependency-resolution flow around p4a.recipe or the pip stage, then inspect how pyproject.toml metadata and site-packages paths are currently handled. Trace where files enter dists//build/ before the Gradle build. Done means an agreed design and implementation path for collecting the declared Android metadata and bundling it into APK builds.

Written by the indexing model from the issue text.