SSE and JSONL streaming endpoints ignore the status_code declared on the path operation and any status code set by a dependency on the Response parameter, always returning 200 while the generated OpenAPI documents the declared code. That makes the schema contradict the actual behavior.

@app.post(/events, response_class=EventSourceResponse, status_code=201)
async def events() -> AsyncIterable[str]:
    yield created
# returns 200, OpenAPI documents 201

Raw streaming responses (response_class=StreamingResponse) already handle both declared and dependency-set status codes via _build_response_args().

This PR applies the same _build_response_args() path to the SSE and JSONL branches. Default behavior is unchanged because the dependency solver's temporary response starts with status_code = None, so no status is injected unless the user declared or set one.

Adds tests/test_stream_status_code.py covering:

• declared status codes for SSE and JSONL streams
• dependency-set status codes for SSE and JSONL streams
• raw streaming as the existing control case
• default 200 behavior for both stream encodings
• OpenAPI status-code consistency