test(order): cover mapInputItemToOfferItem branch behavior

[devorun]

Summary

mapInputItemToOfferItem is the single normalizer every createOrder input item passes through on its way to a Seaport OfferItem, fanning a CreateInputItem out into the fully-populated { itemType, token, identifierOrCriteria, startAmount, endAmount } shape and applying the amount defaults each variant relies on.

It was previously only exercised indirectly through the hardhat-network-backed create-order specs. This adds fast, isolated unit tests in test/utils/order.spec.ts that pin its branch-by-branch behavior:

• basic ERC721 items (both amounts default to 1)
• basic ERC1155 items (endAmount defaults to the start amount; ascending amounts preserved)
• criteria items given an explicit merkle root
• criteria items whose root is derived from identifiers
• currency items: token → ERC20, no token / zero-address → native, and descending end amounts preserved

Testing

• hardhat test (all order util specs pass, 19 total)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.86%. Comparing base (f618d19) to head (c172d2a).
⚠️ Report is 364 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #970      +/-   ##
==========================================
+ Coverage   98.27%   98.86%   +0.59%     
==========================================
  Files          35       45      +10     
  Lines       14526    17775    +3249     
  Branches      660      913     +253     
==========================================
+ Hits        14276    17574    +3298     
+ Misses        245      194      -51     
- Partials        5        7       +2     

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[ryanio]

Taken, thanks. I checked all ten assertions against mapInputItemToOfferItem branch by branch and they match, including the zero-address-is-native case and the endAmount defaults.

Landing in #972, which stacks several contributions because four of them collided in test/utils/order.spec.ts. Yours needed a small conflict resolution against the salt-tag tests from #963 and nothing else. Your commit is in there authored by you. Closing in favor of that.