What changed

• Added a persisted isLockDatabaseOnBack application setting with a default value of true.
• Exposed the option in Application settings under the General section.
• Removed isCloseDatabaseOnExit from GroupsScreenArgs and made Groups back handling read from settings instead.
• Updated Groups back behavior:
  • when the setting is enabled, pressing Back from the root group locks the database and follows the existing exit flow;
  • when the setting is disabled, pressing Back finishes the activity without calling router.exit().
• Updated root navigation so an already-open database starts with GroupsScreen over UnlockScreen; closed databases still start on UnlockScreen.
• Updated activity-level back handling to use OnBackPressedCallback and delegate unhandled back presses through the Cicerone router.
• Moved note editor back handling into the fragment onBackPressed() path.
• Bumped AppCompat from 1.6.1 to 1.7.1.

Why

The previous lock-on-back behavior was passed through screen arguments, which made it depend on navigation entry points. This moves the behavior into a user-facing application setting and keeps root navigation consistent when the database is already open.

The activity and note editor back handling changes are included in this branch because the new root chain/back behavior depends on consistent router-backed back dispatch.

Validation

• ./gradlew app:spotlessApply
• ./gradlew test
• ./gradlew app:compileFdroidDebugKotlin

Notes: validation passed with existing Android Gradle Plugin / resource formatting / deprecation warnings.