#17 removed the `setSessionExpiry` and `isVpnRuntimeAlive` MethodChannel
handlers from MainActivity, and #18 removed their last callers. The Dart
wrappers stayed behind.
Both swallow their errors, so a future caller would not fail loudly — it would
get a silent no-op from `setSessionExpiry` and a permanent
`processAlive: false` from `runtimeState()`, which previously read as "the
tunnel is dead". Deleting them keeps that trap out of the codebase.
`VpnRuntimeState` goes with them; runtime liveness now arrives through the
native status stream, which is generation-scoped. The battery-optimisation
methods are untouched and still used by background_reliability.dart.
Co-Authored-By: Claude Opus 5 <[email protected]>
Claude-Session: https://claude.ai/code/session_019HT2x2JvJNg7XNsJubfHFf
