appLock.ts is imported from the root layout, so an unguarded top-level
`import * as LocalAuthentication from 'expo-local-authentication'` crashes the
whole app at launch on a dev-client built before the dependency was added
("Cannot find native module 'ExpoLocalAuthentication'"). Load it via a guarded
require; if absent → app lock reports `available: false`, everything else runs.
Real builds (EAS / fresh prebuild) ship the module and work normally.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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