Investigate failing ROM suite: `mmc5test_v2_suite`

[mikai233]

Suite

• Name: mmc5test_v2_suite
• TASVideos accuracy-required: Yes
• Notes: MMC5 test set v2

Goal

Make this suite pass (remove ignore) without regressions.

Acceptance criteria

• Identify failing cases / expected behaviour
• Add/adjust tests if needed
• Fix emulator behaviour
• Suite passes in CI

References

• Tracking issue: Failing / ignored ROM suites tracking #38
• README section: Failing / ignored ROM suites (❌)