refactor(EpistemicScale): rehome pure math, drop aggregator

[hawkrobe]

Audit roadmap step F, the close-out: Caratheodory.lean and SignVectors.lean move to Core/Order/ beside FourierMotzkin.lean (mathlib-only files out of the linguistics tree; SignVec to root namespace); the aggregator's theorems (8a/8b/6/2, axiomA_iff_fa, belowCount) extract to a new EpistemicScale/Completeness.lean leaf; EpistemicTag/five_frameworks_agree move beside their MereoTag/LicensingPipeline siblings in Core/Scales/Defs.lean; the aggregator is deleted — the manifest lists leaves directly, mathlib-style. Deferred with rationale: FinAddMeasure → ComparativeProbability/Measure and the Defs/Basic split (high import churn across external consumers; the mixin instances from #109 already connect the layers). Local build was interrupted — CI gates this one.