[feat(Island)] Added a battery alerts plugin to show alerts for charging, low battery and critical battery

[ssethhyy]

Description

This PR adds a plugin for Island that shows alerts on battery indicators like charging, low battery and critical battery. It shows in a long view across the maximum width of the island. It shows the percentage in the right and the battery on the left alongside text displaying what is happening (charging, low battery, critical battery).

Type of change

• Bug fix
• New feature
• UI / visual update
• Performance improvement
• Refactoring / cleanup
• Translations
• Build / CI tooling

UI changes

**Screenshot of Island showing charging alert**



**Screenshots of the battery alerts option inside the Island settings**

Checklist

Before submitting, please make sure:

• The base branch is set to develop (not main).
• The app builds cleanly locally with ./gradlew assembleDebug.
• Unit tests pass with ./gradlew testDebugUnitTest.
• You tested the changes on a device or emulator (including Shizuku or Root if applicable).
• New preferences use SettingsRepository for keys and getter/setter methods.
• New user-facing settings are registered in FeatureRegistry.kt for search indexing.
• New UI follows the design system in ui/core/ (RoundedCardContainer, IconToggleItem, etc.).
• Strings are added to res/values/strings.xml and drawables use rounded variants (R.drawable.rounded_*).

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