Use capacitor-secure-storage-plugin to persist login credentials
(nsec keys) in iOS Keychain / Android KeyStore instead of plaintext
localStorage. Web behavior is unchanged. Existing native users are
auto-migrated on first launch: if secure storage is empty but
localStorage has data, it is moved over and the plaintext copy is
removed.
Also ignore ios/ directory in ESLint (Capacitor-generated files).
Alex Gleason