PRL Submission v1.0.0

Gravitational Decoherence Rate Scales as cos²θ with Measurement Basis

Core prediction: Γ(θ) = Γ₀cos²θ
Key signature: τ(45°)/τ(0°) = 2

Author: Kafkas M. Caprazli
ORCID: 0000-0002-5744-8944

Paper ready for Physical Review Letters submission.