Fix missing redeemer causing null scriptIntegrityHash in mint transaction

[Copilot]

Mint transactions were rejected on-chain with error 3113 because the transaction body had scriptIntegrityHash: null. The Cardano node computed a non-null expected hash, meaning the transaction was missing the field entirely.

Root Cause

The Evolution SDK only computes scriptDataHash when redeemers.length > 0. Since mintAssets was called without a redeemer, no redeemer was tracked in builder state, the hash was never computed, and the resulting transaction body omitted scriptIntegrityHash — required for any transaction executing a Plutus script (even via reference).

Changes

• src/mint.ts — Add void redeemer to mintAssets; import Data:

.mintAssets({
  assets: Assets.fromRecord({ [token]: amount }),
  redeemer: Data.constr(0n, []),
})

The Aiken validator accepts _redeemer (ignored), so Data.constr(0n, []) is sufficient to trigger scriptDataHash computation with the correct Plutus V3 language views.

• src/mint.test.ts — Mirror the same redeemer in the test builder for consistency.

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