Explicit Isolation Bounds for Zeta Zeros at Fixed Small Spacings: Signed Complex-Block Allocation and a Certified Fourier Test

This independent preprint develops a complex finite-multiset inequality using signed Hilbert-space blocks and a deterministic allocation of screening centers. Coupled with unconditional fixed-test weighted pair correlation, Conrey's integrated off-line zero-density estimate, and strict computer-assisted Fourier interval certificates for an explicitly smoothed forty-mode density, the method yields proposed quantitative isolation bounds for zeta zeros at two fixed locally normalized spacings: more than 0.655208 at c=0.00575 and more than 0.655200 at c=0.005966. A sharp real-supported forest inequality identifies a simpler benchmark. The signed decomposition itself is not claimed as new over Lamzouri. The new complex blocking and numerical package await external specialist verification; this preprint does not prove RH/GRH or any positive lower density of non-isolated zeros.