feat(mef): compose QEF credits and audit filing evidence

[a7ul]

Combined credits and filing evidence

Public source returns
        |
 Education -> Adoption -> QEF tax refigure
        |                     |
 Native XML + PDF       Source replay guards

ATS scenarios -> 120 individual observations
                 calculations / copies / attachment

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• Combined credits and unused adoption credit previously blocked QEF returns, while component successes obscured complete filing evidence.
• Both tax runs now settle education before adoption and preserve only the actual carryforward; 55 grouped tests pass, with four schema-valid packets and 42 reviewed pages.
• Export audits retain 42 method-change, 21 fuel-credit and 48 New Markets passes, plus 90 debt-cancellation passes and two deferred cap failures across seven schema-valid packets and 29 reviewed pages.
• The ATS ledger preserves 120 observations and 40 of 54 evaluated nonprovisional calculation matches, anchoring the provisional 75% estimate and 50–85% judgment range.
• Pending-JSON reload still rejects source replay and is recorded as deferred item150; all 52 parent tasks and external source-authentication requirements remain open.