feat: add correction activation status

[zefutoff]

Summary

• add a dedicated correction status screen
• show the real Android native spell-checker selection state
• show Grammalecte IME disabled / enabled / currently selected states
• refresh status when returning from Android settings
• refresh IME state immediately when the keyboard picker closes
• provide direct access to spell-checker and input-method settings
• keep the status activity internal and non-exported
• centralize correction-status detection for reuse by the main screen
• mark the final Phase 3 roadmap item complete

Validation

• native spell-checker state manually validated on Samsung Galaxy S21 / Android 15
• IME disabled -> enabled -> selected transitions manually validated
• status refresh after Android settings return validated
• immediate refresh after closing the IME picker validated
• manifest test verifies the status activity is not exported
• make check
• make assemble
• git diff --check
• final APK does not request android.permission.INTERNET

Roadmap

This completes Phase 3 — User controls.