E: The Enthalpy Bank — The Zhangyu Standard, the Four-Layer Asset Architecture, and the 2.0 ZY Bankruptcy Firewall

Supplementary to the core N.E.A. sequence. The preceding volumes of the N.E.A. series have constructed the complete physical and biological account of reality. G established the derived principles and the Being Tax B=1. T established the Tiling Audit and Force-Body Duality. U established the Sole Boson Proposition and defined the Zhangyu (ZY) as the universal unit of topological value. O established the layered coupling architecture of relativity and quantum mechanics. C proved that complex systems are virtual carrier structures performing anisotropic arbitrage. With the currency defined and the hardware audited, this volume constructs the Enthalpy Bank—the four-layer accounting ledger in which all physical, biological, civilizational, and cognitive assets are denominated in Zhangyu (ZY). We provide rigorous ZY-denominated proofs of the dimensional uniqueness theorem (d=3 is the only solvent integer dimension under finite bandwidth), the quantitative elimination of the Luxury Solids as physical force carriers, and the 2.0 ZY Bankruptcy Firewall as the absolute topological liquidation threshold. We establish the Shared Edge Dividend Lemma, which resolves the apparent degree ambiguity in the C8 tiling scaffold, and the Locking Premium Theorem, which explains the effective logical degree of fully locked K4 simplexes under SU(3) confinement. The four layers are: Layer I (Physical Infrastructure, H=1.3333 ZY), Layer II (Biological Efficiency, H≈1.25 ZY), Layer III (Civilizational Credit, H≈1.15 ZY, illustrative heuristic benchmarks), and Layer IV (Observer Sovereignty, H≈1.0117 ZY, heuristic). The Protocol Vacuum Zone between 2.0 ZY and 3.0 ZY is formally defined as a conceptual regime of degraded operation. The Law of Topological Diminishing Returns and the ΔH≤0 evolutionary constraint provide the theoretical foundation for relaxation oscillator dynamics governing civilizational cycles. The tiling origins of value are established: the Zhangyu is the universal unit of "failed space"—the rent paid when a geometric carrier cannot tile and is forced to exist as localized matter rather than diluted background. No freely adjustable continuous parameters in the topological sector; anchored and candidate coefficients are explicitly listed. Five quantitative figures provide numerical validation across physical, biological, and civilizational scales.