Quadratic Persistence under General Disturbance: Stability of Admissible Comparability Functionals (IM-B003, v0.3)

This document is part of the Informational Mechanics (IM) framework and is published in the IM-B (Calculus & Admissibility) series within the IM v0.3 corpus. The paper extends the structural uniqueness result of IM-B002 by analyzing quadratic persistence under general disturbance processes. It shows that strength functionals satisfying orthogonal additivity and invariance remain uniquely stable under Gaussian disturbance, and classifies the conditions under which non-Gaussian perturbations preserve or break quadratic structure. The result is purely mathematical and introduces no physical axioms, dynamics, interpretations, or empirical claims. Its purpose is to establish disturbance-stability conditions within the admissible mathematical domain and to provide structural lemmas intended for potential downstream use in IM-E (Measurement & Operators) and IM-D (Core Physics) papers. No claim is made that any particular physical system must satisfy the assumptions stated here.