f - Update changelog to use SpliceNegotiationFailed name

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: jkczyz

pending_changelog/4388-splice-failed-discard-funding.txt

@@ -1,21 +1,21 @@
 # API Updates
 
- * `Event::SpliceFailed` no longer carries `contributed_inputs` or `contributed_outputs` fields.
+ * `Event::SpliceNegotiationFailed` no longer carries `contributed_inputs` or `contributed_outputs` fields.
    Instead, a separate `Event::DiscardFunding` event with `FundingInfo::Contribution` is emitted
    for UTXO cleanup.
 
  * `Event::DiscardFunding` with `FundingInfo::Contribution` is also emitted without a
-   corresponding `Event::SpliceFailed` when `ChannelManager::funding_contributed` returns an
+   corresponding `Event::SpliceNegotiationFailed` when `ChannelManager::funding_contributed` returns an
    error (e.g., channel or peer not found, wrong channel state, duplicate contribution).
 
 # Backwards Compatibility
 
  * Older serializations that included `contributed_inputs` and `contributed_outputs` in
-   `SpliceFailed` will have those fields silently ignored on deserialization (they were odd TLV
+   `SpliceNegotiationFailed` will have those fields silently ignored on deserialization (they were odd TLV
    fields). A `DiscardFunding` event will not be produced when reading these older serializations.
 
 # Forward Compatibility
 
  * Downgrading will not set the removed `contributed_inputs`/`contributed_outputs` fields on
-   `SpliceFailed`, so older code expecting those fields will see empty vectors for splice
+   `SpliceNegotiationFailed`, so older code expecting those fields will see empty vectors for splice
    failures.