Theorem on the absence of asymptotic chaos

<jats:p>Note on this consolidation This document merges three previously separate pieces (A GitHub repository with numerical checks has been added) (1) The No-Chaos Theorem, now in its corrected form: ontic chaos is impossible (§5), and - after two earlier, retracted attempts (a geometric leakage estimate with the wrong sign; an entanglement-growth mechanism that conflated entropy growth with a Lyapunov exponent and depended silently on ETH) - dynamical chaos at any fixed coarse-graining scale ℓ is proven structurally impossible (§7), with level statistics introduced as the one chaos diagnostic that survives (§7.3). (2) The thermalization content that used to be misattributed to "chaos": real physics (Calabrese–Cardy growth, Page saturation), relocated here as what it actually is (§9), together with its genuine connection to the construction used elsewhere in this work via ETH. (3) New in this consolidation: the Embedded-Observer No-Go Theorem (§8), which answers a related but logically distinct question - not whether an observer sees chaos, but whether an observer confined to a proper subgraph can ever completely reconstruct the global state or evolve autonomously. This is a better-grounded reason for an embedded observer's limited picture of reality than either chaos or thermalization, and does not depend on ETH, Page's theorem, or any genericity assumption beyond an entangling (generic) boundary coupling.</jats:p>