Fix callback subscription cleanup and native event lifecycle

[nicolas-chaix-didomi]

Fix event listener cleanup that can cause ready/error callbacks to time out despite receiving a native event.

• Remove only the completed or timed-out call’s subscription, preserving other pending calls.
• On iOS, use observation state instead of bridge presence to gate events, and remove the native SDK listener during module invalidation.
• On Android, route all events through emitDeviceEvent().

Adds regression tests.