bug: on-chain send that never reached the network shows outcome unknown instead of not sent #968

Refs:

• bug: on-chain payment after app resume never broadcasts and is dropped as outcome unknown #967
• fix: report on-chain broadcast outcomes ldk-node#119

What happened?

When every broadcast attempt of an on-chain send fails before the request reaches the Electrum server (no network, connection refused, broken pipe on write), Bitkit shows "Payment Pending: This transaction may have been sent. Its outcome is unknown." The payment was not sent, and the user is told not to retry. ldk-node reports this case as Unknown, the same as a lost reply, so the app cannot tell the two apart.

Expected behavior

• ldk-node reports a broadcast that reached no server as not sent.
• Bitkit then says the payment was not sent, rolls back the Paykit proof, releases the coins and offers a retry.
• A lost reply or a timeout keeps today's outcome-unknown handling.

Steps to Reproduce

1. Turn off networking, or block the Electrum server.
2. Pay a Paykit payment request on-chain.

Logs / Screenshots / Recordings

Failed to broadcast transaction 226500f2…c280: Made one or multiple attempts, all errored: Broken pipe (os error 32) x3
On-chain broadcast outcome unknown for 226500f2…c280 [SendConfirmationView.swift:1348]

Bitkit Version

3.0.0 (200)

Device / OS

iOS, all devices

Reproducibility

Always, whenever no broadcast attempt reaches the server.

Additional context

Split from #967, whose reconnect fix and automatic rebroadcast ship first. This one needs a new ldk-node outcome (NotSent) and a matching app branch.