feat(tests): add max-code-size jumpdest test for immediate bytes

[danceratopz]

🗒️ Description

Follow-up to #2993, from a review idea by @LouisTsai-Csie: extend the max-code-size jumpdest coverage to a 0x5B that lands in an instruction's immediate bytes: #2993 (review)

test_max_code_size_jumpdest_in_immediate puts a 0x5B as the last byte of a MAX_CODE_SIZE contract, right after an immediate-carrying opcode, and jumps to it:

• PUSH1: the 0x5B is push data, always skipped, so it is not a JUMPDEST and the jump is rejected.
• DUPN/SWAPN/EXCHANGE: per EIP-8024 the 0x5B is an invalid immediate that is not skipped, so it stays a valid JUMPDEST and the jump is accepted.

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The additional benefit is marginal. EIP-8024 already tests this immediate classification (on small contracts), and #2993 already proves the jumpdest scan survives to 64 KiB. The only thing this uniquely catches is a client whose immediate-skipping logic is size-bounded independently of the main jumpdest pass: it would pass both existing suites yet break on an EIP-8024 immediate near the new max. Obscure and unlikely, since real clients run one linear pass over the whole code.

Cost is negligible (sub-second t8n per case), so I'm not precious about it: happy to merge or close as people see fit.

🔗 Related Issues or PRs

• Follows up feat(tests): add EIP-7954 jumpdest test past the old code-size limit #2993 (idea from @LouisTsai-Csie's review there).
• EIP-7954 tracker: EIP-7954 Implementation Tracker: Increase Maximum Contract Size #2028
• Test release tracker: Test Release Tracker: glamsterdam-devnet@v6.0.0 #2915 (glamsterdam-devnet@v6.0.0)

✅ Checklist

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

  just 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.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.20%. Comparing base (c00006f) to head (0c646cc).
⚠️ Report is 1 commits behind head on forks/amsterdam.

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #2998   +/-   ##
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  Coverage            93.20%   93.20%           
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  Files                  620      620           
  Lines                38759    38759           
  Branches              3341     3341           
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  Hits                 36127    36127           
  Misses                1773     1773           
  Partials               859      859           

Flag	Coverage Δ
unittests	93.20% <ø> (ø)

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[LouisTsai-Csie]

Thanks! This is what i want.