Trim changelog to the exported unionWith change

Author: Unisay

plutus-ledger-api/changelog.d/20260527_131134_yuriy.lazaryev_issue_2243_fused_unionwith.md

@@ -1,9 +1,3 @@
 ### Changed
 
-- Fused `unionWith` in `PlutusLedgerApi.V1.Data.Value` into two outer passes (`Map.union` + a single `Map.map`), down from the previous three. The discarded `unionVal` helper returned a full `Map CurrencySymbol (Map TokenName (These Integer Integer))` that `unionWith` then re-traversed; folding it in removes that second outer walk, and a currency present on only one side now has its token map mapped once rather than wrapped and then re-mapped. The `Map.union` lookup-and-merge core is unchanged, so this is a constant-factor improvement, not an algorithmic one.
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-- Fused `checkBinRel` along the same shape, walking the outer `Map.union` with `Map.all` and applying the relation against `0` on whichever side is missing. The inner per-currency merge now sits inside the `Map.all` predicate rather than in a separate eager pass, so the walk's short-circuit on the first failing pair also skips the inner merges of every later currency — previously the whole merged structure was built before any check ran. `geq` / `leq` / `gt` / `lt` inherit this early exit.
-
-### Removed
-
-- The internal `unionVal` and `checkPred` helpers from `PlutusLedgerApi.V1.Data.Value`. Both were module-internal (not exported); their only call sites — `unionWith` and `checkBinRel` — now do the merge directly.
+- Optimised `unionWith` in `PlutusLedgerApi.V1.Data.Value`: same semantics and signature, but the merge now runs in two outer passes instead of three. A constant-factor speedup, not an algorithmic one.