bug: pubky authorize can hang on authorizing during a busy session restore #993

Refs:

• fix: keep a pending pubky sign-in link when another link opens #987
• paykit private_payments policy error stalls restore and profile re-creation #984
• profile deletion makes ~100 sequential homeserver requests pubky/paykit-rs#197

What happened?

Tapping Authorize on a Pubky sign-in sheet sometimes hangs on "Authorizing…": nothing is logged, the relay never receives the approval, and the sheet cannot be dismissed. @jvsena42 saw it in 4 of 6 attempts on #987 and 1 of 3 on master, each time with Deferred session restoration and SharedStateBusy warnings in the log (comment).

Expected behavior

Authorize completes, or fails with an error the user can act on, and the sheet can always be closed.

Steps to Reproduce

1. With a Pubky profile in Bitkit, open a bitkit://pubky-auth/signin link on a cold start, so the session restore is busy.
2. Tap Authorize and enter the PIN.
3. The sheet can stay on "Authorizing…" with nothing in the log.

Additional context

It coincides with Paykit shared-state contention during the session restore; synonymdev/bitkit-android#1543 removed the same wait on Android by letting approval need only the platform setup.