fix(gateway): SSE terminality, deadline, error-mapping fidelity (GW-03..GW-07, GW-12..GW-14)
- GW-04: /subscribe error events are terminal — scan-based emission of
the error frame, then end of stream (matches call.error semantics).
- GW-05: enforce the 30 s gateway deadline via tokio::time::timeout in
GatewayDispatch::invoke; hung handlers surface as TIMEOUT (504),
streaming/sink stay unbounded per ADR-021.
- GW-07: gateway error paths route through the new identity-aware
call_error_to_http_response_with_identity; retryable HTTP_429/HTTP_503
now carry Retry-After on /call, /batch, /search, /schema, /publish.
- GW-13: SSE keep-alive (15 s comment frames) + retry: 15000 field.
- GW-14: module doc fixed (6 endpoints; /publish lives in routes.rs).
- GW-03/GW-12: mapping rides d7ee302's INVALID_OPERATION_TYPE mapper
(documented in http-server.md table); 200-on-stream asymmetry
documented.
Verification: cargo test (243 passed); cargo clippy --all-targets -- -D
warnings clean; cargo fmt --check clean.
glm-5.3-flash
9bc9e669e1