Instances are no longer disposed on unmount

SanityApp and ResourceProvider no longer dispose their Sanity instance when they unmount. The instance, and the stores it created, now live until the page reloads. This fixes SDK apps crashing when React <Activity> hides and shows them, since React runs the same cleanup for a hidden tree as for an unmounted one.

If you relied on unmounting to clean up, for example between tests, create the instance yourself with the same config, render SanityApp inside <SanityInstanceProvider instance={instance}>, and call instance.dispose() when you are done.

• Session and hook telemetry now include runtime context, and hook-mounted and session-ended events include the session auth method. This lets analytics segment Studio and app usage independently of credential source.