- build_request takes the op's input_schema and rejects undeclared
input keys (INVALID_INPUT) before any outbound request is built;
explicit `additionalProperties: true` opts into catch-all input;
non-object inputs rejected (OAI-02)
- in: header parameters are stamped `wire: header` in the generated
input schema and sent as upstream request headers, not query params;
in: cookie fails import with a clear error (OAI-03)
- a spec parameter named `body` is rejected at import unconditionally
(OAI-07)
- FromJsonSchema::new returns Result and validates method/path template/
base_url at construction; registered visibility forced to Internal
like from_openapi; module doc corrected (OAI-09)
Verified: cargo test, cargo test --all-features, clippy (both feature
sets, -D warnings), cargo fmt --check