bug: on-chain payment waits up to 20 s on the connecting screen after resume #978

Refs:

• fix: reconnect electrum after the server drops the connection ldk-node#127
• fix: wait for the bitcoin network before an on-chain payment after resume #975

What happened?

When Bitkit returns from the background and the Electrum server has dropped the connection while an on-chain wallet sync was waiting on it, that sync stays stuck until its 20 s timeout (BDK_WALLET_SYNC_TIMEOUT_SECS in ldk-node). Every later sync waits for it, so an on-chain payment opened right after resume sits on the "Connecting to network" screen for up to 20 s. ldk-node already rebuilds the connection within about a second (synonymdev/ldk-node#127), but the stuck sync still holds the wait.

Expected behavior

After the connection is rebuilt, a new on-chain sync runs on it without waiting for the stuck one, so the payment screen opens within a few seconds of resume.

Steps to Reproduce

1. Leave Bitkit in the background until the Electrum server drops the idle connection, with an on-chain sync in flight.
2. Open a Pubky Shop on-chain payment right after returning.
3. The connecting screen shows for about 20 s.

Logs / Screenshots / Recordings

Recording in #975: the connecting screen shows from 15:16:55 to 15:17:15 UTC, ended by the first sync after the stuck one's timeout.

Bitkit Version

3.0.0 RC3 (ldk-node 0.7.0-rc.76)

Device / OS

iOS, all devices

Reproducibility

Whenever the stuck call on the dropped connection is the on-chain sync; a stuck fee update or balance lookup recovers in 1-3 s.

Additional context

The fix is in ldk-node: abandon or bypass an in-flight on-chain sync once its client has been replaced, instead of making later syncs wait for it. Android shows no post-resume wait screen, so this is only a latency there (about 10 s before the next sync in a device gate on synonymdev/bitkit-android#1532).