v1.9.0 — Library architecture convention

Adds §13.7: a normative cross-language library-architecture convention so the same protocol in different languages is structurally common. Defines the canonical module taxonomy with names identical across Go/Rust/C++ (the adapt adapter, mock, virtual, and a standard module-name registry), and the local-relay-module rule pending published bindings. SpecVersion 1.9; REQ-RELAY-087. Additive MINOR.