Add safety identifier to responses API

[lzell]

Example of passing a safety identifier:

let requestBody = OpenAICreateResponseRequestBody(
    input: .text("hello world"),
    model: "gpt-4.1-mini",
    safetyIdentifier: "123",
)

let response = try await openAIService.createResponse(
    requestBody: requestBody,
    secondsToWait: 120
)
print(response.outputText)

[lzell]

Available in 0.127.0 https://github.com/lzell/AIProxySwift/releases/tag/0.127.0