Add budget consistency test (VariantC, 55 builtins)

[Unisay]

Summary

• Adds a test that verifies all three CEK evaluation paths produce identical ExBudget for a single "kitchen sink" UPLC term exercising 55 builtins available at changPV (PV9, batch 1–4)
• The three paths: direct (defaultCekParametersForVariant), benchmark (mkDynEvaluationContext), and production (V3.mkEvaluationContext with [Int64])
• Confirms that noinline vs inline and JSON round-trip differences do not affect budget calculation

Context

Addresses the concern from https://github.com/IntersectMBO/plutus-private/issues/2084 that different cost model construction paths might produce divergent budgets.

Builtin coverage

Category	Count	Examples
Integer arithmetic	10	AddInteger, DivideInteger, EqualsInteger
ByteString ops	8	AppendByteString, SliceByteString, IndexByteString
Crypto hashes	5	Sha2_256, Blake2b_256, Keccak_256
String ops	4	AppendString, EncodeUtf8, DecodeUtf8
Data ctors/dtors	15	IData, UnConstrData, SerialiseData, MkPairData
Conversion	2	IntegerToByteString, ByteStringToInteger
1-Force polymorphic	8	IfThenElse, HeadList, MkCons, Trace, ChooseData
2-Force polymorphic	3	FstPair, SndPair, ChooseList

Not covered: BLS12_381 (need group elements), signature verification (need valid sigs), batch 5-6 (not available at changPV).

Test results

All three paths agree: ExBudget {exBudgetCPU = ExCPU 19495026, exBudgetMemory = ExMemory 37516}

Test plan

• cabal test plutus-ledger-api-test --test-option="-p" --test-option="/Budget consistency/" — all 5 tests pass
• CI passes