Function loadWalletEvents

Builds a robust loading stream for a wallet's events that emits WalletLoaderStatus updates.

For every change to the relay set it:

1. Backfills wallet, token, history and (when WalletLoaderOptions.useDeleteEvents is enabled) delete events with NIP-77 sync or paginated requests.
2. Opens a live subscription to all relays to keep the wallet up to date. Failures are retried by the pool.

All received events are written to the event store and every step emits debug logs. Subscribe to start loading and unsubscribe to tear it down.