This paper presents Project Angelica — a novel buffer layer architecture for GaN-on-Si(111) heteroepitaxy based on a gadolinium oxide (Gd₂O₃) interlayer with asymmetric interface coupling. The core innovation lies in the deliberate engineering of two fundamentally distinct interface mechanisms: a Van der Waals weakly-coupled bottom interface (Si/Gd₂O₃) enabling atomic-scale controlled slippage, and a strongly-bonded covalent top interface (Gd₂O₃/GaN) providing a high-quality epitaxial template. Combined with a dense-to-dilute compositional grading profile — herein designated Angie's Grading — described by C(z) = (1−z)^α with α ≈ 0.10, and multi-objective optimization via Differential Evolution algorithm, the architecture achieves the following simulated results: Residual thermal stress reduced from 1110 MPa to 127.5 MPa (−88.5%) 2DEG sheet electron density increased 3.14× to 1.28×10¹³ cm⁻² AlGaN aluminum content safe limit extended from 7.3% to 22.9% Cut-off frequency fT = 116 GHz (Lg = 0.15 μm) Maximum oscillation frequency fmax = 147 GHz Noise figure NF = 0.51 dB at 28 GHz Estimated fatigue life: 2.7 million thermal cycles Maximum operating temperature: 350°C The architecture is directly compatible with existing MOCVD production equipment. Complete fabrication specifications, tolerance analysis, and simulation source code are provided to enable immediate laboratory validation by the research community. Keywords: GaN-on-Si, HEMT, heteroepitaxy, buffer layer, Gd₂O₃, rare-earth oxide, stress compensation, Van der Waals epitaxy, compositional grading, 2DEG, RF power amplifier, heterogeneous integration Version 2 updates the license from CC BY-NC 4.0 to CC BY 4.0 International (paper/documentation) + Apache License 2.0 (simulation source code). All content is now fully open.