Add native note translation with browser fallback

[silentpatch-agent]

Closes #1055.

Summary

• add a Translate Note action to the note menu
• use the native Android ACTION_TRANSLATE service when available
• fall back to Google Translate with the note and current app language encoded in the URL
• cover the native and fallback paths with Robolectric tests

This keeps translation provider-neutral on supported devices, requires no API key, and still works on older devices without a translation service.

Verification

• ./gradlew :app:ktlintCheck
• ./gradlew :app:detekt