QSA mathematical representation fidelity evidence

[Inserian]

Adds an explicit fidelity/evidence contract to the accepted QMath language compiler so downstream Brain/QSA integrations can distinguish exact algebraic mathematics from exact structural representations and bounded numerical approximations without collapsing those evidence classes into one exact flag.

The child preserves every accepted PR74 route and adds:

• QMathFidelity::{Unverified, ExactAlgebraic, ExactStructural, BoundedNumerical};
• finite nonnegative absolute/relative error-bound receipts for bounded numerical evidence;
• separate source/type/dimensional, coefficient-arithmetic and phase-arithmetic evidence;
• automatic exact-algebraic classification and exact QRational extraction for closed rational QMath expressions;
• exact rational comparison execution (==, !=, <, <=, >, >=) over admitted typed values;
• exact-structural classification for unresolved symbolic QMath expressions;
• exact algebraic + exact phase evidence for Weyl, cyclotomic qutrit and qutrit Clifford routes;
• compatibility with the existing receipt.exact field, now derived from the stronger evidence class.

The existing QMath carrier now directly gates structural-vs-algebraic classification, exact closed-rational execution, exact comparisons, bounded-numerical error validation, nonfinite/negative-bound rejection, and fidelity retention across qubit, mixed-dimensional Weyl, qutrit cyclotomic and Clifford routes.

This is a research-only stacked child of accepted PR74. It does not parse language, change Brain semantics/procedure binding, mutate training, alter production routing, or grant merge authority. Its purpose is to make QSA safe to use as the mathematical/physics substrate beneath Brain-owned semantic/procedure admission without overstating floating or approximate backends as exact algebra.