[CHIA-4364] more hardening of FF logic

[arvidn]

Note

Medium Risk
Touches consensus mempool FF eligibility for relative timelocks. Logic is a small, well-tested flag clear, not a consensus rule change.

Overview
Hardens mempool fast-forward eligibility so a dropped relative timelock (SkipRelativeCondition) still clears ELIGIBLE_FOR_FF. Those conditions are trivially true (negative “after” or overflowing “before”) but remain relative timelocks.

Tests now cover those no-op relative values on ephemeral spends (still EphemeralRelativeCondition) and confirm they also disqualify FF, while matching absolute skips do not.

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[coveralls-official]

Coverage Report for CI Build 32455163375

Coverage increased (+0.005%) to 81.922%

Details

• Coverage increased (+0.005%) from the base build.
• Patch coverage: 5 of 5 lines across 1 file are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	20052
Covered Lines:	16427
Line Coverage:	81.92%
Coverage Strength:	11573659.53 hits per line

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💛 - Coveralls

[arvidn]

@cursor review

[cursor]

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