Metadata table for lora's namespaced builtin functions.
Owned by this leaf crate so the analyzer (which validates function
references at compile time), the executor (which dispatches on the
op strings), and the editor's WASM bridge (which feeds the
autocomplete / signature-hint surface) can all share a single
declaration. Drift-safety tests in lora-executor assert that every
entry here has a dispatch arm.
This is intentionally more than an arity table: enum-like argument slots live here too, so analyzer rewrites and executor dispatch share one declaration for each builtin.