Fail funding payments lost to a confirmed conflict

Since declining to adopt a conflicting close's confirmation, a funding
payment whose transaction was double-spent stayed Pending forever --
nothing wrote a terminal status for an on-chain record -- and the sync
loop kept re-queueing the dead transaction for rebroadcast on every
tip change.

Mark such a record Failed once a conflict from outside its candidate
history has confirmed through ANTI_REORG_DELAY while neither its own
transaction nor any RBF candidate can still confirm, mirroring the
anti-reorg finality the Succeeded transition already assumes. Removing
the payment's pending entry then stops the re-queueing.

Settling also removes the entry that maps candidate txids to the
record, so a later wallet event for a dead candidate falls back to
keying by that candidate's txid -- which, for the first candidate, is
the record's own id. Skip such events rather than let the generic
handling resurrect the settled record, and let a replayed replacement
event finish an entry removal a crash interrupted instead of stamping
the terminal status into the leftover entry.

Implemented with Claude Code.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: jkczyz