fix precompile tests, add precompile test cases from besu-native

[garyschulte]

fix main test target to include precompile tests, fix errors, add test cases from besu-native

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Note

Medium Risk
Changes affect cryptographic precompile input validation and pairing semantics (e.g., empty BLS12 pairing input), which can alter execution outcomes; however, behavior is now backed by extensive upstream test vectors.

Overview
Wires src/precompile/main.zig into the Zig build as a dedicated b.addTest target so precompile unit tests run via the normal test step (instead of only via a custom CI zig test invocation), and ensures main.zig actually executes tests.zig via a top-level test block.

Tightens precompile correctness: bls12PairingRun now rejects empty input per EIP-2537 expectations, and BN254 point validation is upgraded from a stub to enforce EIP-196/197 field-modulus bounds (with explicit infinity handling). Also fixes a RIPEMD-160 long-message expected digest.

Adds large, vector-driven test coverage for BN254 and BLS12-381 precompiles by porting Besu CSV suites (new *_tests.zig plus embedded testdata/*.csv), including error-path cases and gas checks for fixed-cost operations.

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