Part I: The Self-Enrichment Principle
The enrichment ladder is the architectural spine of the entire series. We prove the Canonical Ladder Theorem: the self-enrichment of Category τ produces exactly four layers E₀, E₁, E₂, E₃—non-empty, strictly nested, and saturating at E₃. No fifth layer introduces new ontic structure.
Why exactly four layers? Because the seed orbit ρ generates exactly four orbits under the ABCD decomposition, and the enrichment functor inherits this four-fold structure. This explains the series architecture: E₀ gets three books (the mathematical kernel is rich), E₁ gets two (fibre and base split the physics), E₂ and E₃ get one each. Each layer has the uniform template (Carrier_k, Predicate_k, Decoder_k, Invariant_k).