feat: add EUC benchmark

[DavePearce]

This adds a benchmark corresponding to the "Tiny Euclidean Division Module (EUC)".

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Note

Adds the EUC assembly benchmark and test, introducing euc.zkasm for 64-bit division validation and quotient ceiling.

• Benchmarks/Tests:
  • Add Test_AsmBench_Euc invoking asm/bench/euc for field.BLS12_377 in pkg/test/assembly_bench_test.go.
• Assembly:
  • Add testdata/asm/bench/euc.zkasm implementing fn euc(DIVIDEND, DIVISOR=1, QUOTIENT, REMAINDER) -> (CEIL):
    • Ensures non-zero divisor, reconstructs and validates dividend, checks REMAINDER < DIVISOR, and computes CEIL (QUOTIENT or QUOTIENT + 1).

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