feat(test-benchmark): add precompile macro for precompile benchmarks

[LouisTsai-Csie]

🗒️ Description

Precompile benchmark tests previously used Op.STATICCALL as target_opcode, which made the fixture metadata ambiguous: Every precompile showed the same opcode name. This PR introduces descriptive per-precompile labels (e.g. ECRECOVER, BN128_ADD, BLAKE2F) so the fixture _info.metadata.target_opcode field clearly identifies which precompile is being benchmarked.

A new OpcodeTarget dataclass pairs a display name (written into the fixture) with the underlying opcode (used for --fixed-opcode-count validation):

@dataclass(frozen=True)
class OpcodeTarget:
    name: str
    opcode: Op

This keeps OpcodeTarget general-purpose: it is not precompile-specific. Any future benchmark that needs a human-readable label while counting a different EVM opcode can reuse it.

A Precompile helper in the test helpers collects all precompile targets:

class Precompile:
    ECRECOVER = OpcodeTarget("ECRECOVER", Op.STATICCALL)
    SHA256 = OpcodeTarget("SHA2-256", Op.STATICCALL)
    ...

The _verify_target_opcode_count method resolves OpcodeTarget.opcode for the count lookup, so --fixed-opcode-count validation still works correctly against the real STATICCALL counts.

🔗 Related Issues or PRs

N/A.

✅ Checklist

• All: Ran fast tox checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  uvx tox -e static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.
• Tests: For PRs implementing a missed test case, update the post-mortem document to add an entry the list.
• Ported Tests: All converted JSON/YML tests from ethereum/tests or tests/static have been assigned @ported_from marker.

Cute Animal Picture

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.24%. Comparing base (fd1dd63) to head (9e8d00a).
⚠️ Report is 5 commits behind head on forks/amsterdam.

Additional details and impacted files

@@                 Coverage Diff                 @@
##           forks/amsterdam    #2591      +/-   ##
===================================================
- Coverage            86.35%   86.24%   -0.12%     
===================================================
  Files                  599      599              
  Lines                36904    36984      +80     
  Branches              3771     3795      +24     
===================================================
+ Hits                 31868    31895      +27     
- Misses                4485     4525      +40     
- Partials               551      564      +13     

Flag	Coverage Δ
unittests	86.24% <ø> (-0.12%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.