execution/abi: reject invalid int/uint bit widths in NewType

[lmorett1]

Reject invalid int/uint widths at ABI type parsing, and align pack/unpack tests to valid big.Int width cases.

[Copilot]

Pull request overview

Tightens ABI type parsing in execution/abi by rejecting invalid int<M>/uint<M> bit widths at NewType time, and updates packing/unpacking/type-check tests to use valid widths while still exercising the *big.Int paths.

Changes:

• Add validation in NewType to require 8 <= M <= 256 and M % 8 == 0 for int<M> and uint<M>.
• Update pack/unpack tests to use int72/uint72 instead of invalid int17/uint17.
• Adjust type-check expectations and add new test cases to ensure out-of-range widths are rejected.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
execution/abi/type.go	Enforces valid ABI bit-width constraints for int/uint in NewType.
execution/abi/type_test.go	Updates error expectations for invalid widths and adds new invalid-width coverage.
execution/abi/packing_test.go	Switches invalid int17/uint17 test types to valid int72/uint72 while keeping *big.Int behavior exercised.
execution/abi/unpack_test.go	Same as packing tests: uses valid widths to keep big-int decoding paths under test.

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