fix(sdk): flatten createTranscription and createSpeech method signatures

[charlesrockhead-OR]

Summary

openrouter.stt.createTranscription({ model, inputAudio }) and openrouter.tts.createSpeech({ model, input }) did not compile against @openrouter/sdk v0.12.28 — the request body was wrapped under a sttRequest / speechRequest field, so callers had to write { sttRequest: { model, inputAudio } }.

This was caused by Speakeasy's maxMethodParams heuristic: STT and TTS each had 4 parameters (the request body plus 3 globally-injected app-identification headers — HTTP-Referer, X-OpenRouter-Title, X-OpenRouter-Categories). With 4 > the per-route override of 1 in x-speakeasy-max-method-params, Speakeasy collapsed everything into a single wrapper object, defeating the override.

Fix

Add x-speakeasy-globals-hidden: true on the per-operation declarations of those headers for /audio/transcriptions and /audio/speech only, via the existing add-headers.overlay.yaml. Per Speakeasy's docs, this hides the global from the per-call method signature while keeping it set via the SDK constructor. The body is then the only parameter Speakeasy counts, so it rides at the top of the method signature instead of being wrapped.

API change

// Before
openrouter.stt.createTranscription({
  sttRequest: { model: "openai/whisper-large-v3", inputAudio: { data, format: "wav" } },
});

// After
openrouter.stt.createTranscription({
  model: "openai/whisper-large-v3",
  inputAudio: { data, format: "wav" },
});

Same for openrouter.tts.createSpeech.

What's unchanged

• Wire behavior. HTTP-Referer / X-OpenRouter-Title / X-OpenRouter-Categories are still emitted on every STT/TTS request from client._options.httpReferer / appTitle / appCategories. See src/funcs/sttCreateTranscription.ts and src/funcs/ttsCreateSpeech.ts — the header injection block is identical to before.
• Constructor surface. new OpenRouter({ httpReferer, appTitle, appCategories }) works exactly as before.
• All other methods. chat.send, embeddings.generate, responses.send, guardrails.*, videoGeneration.generate, etc. still accept their existing wrapped request shape and still expose per-call header overrides.

Breaking change for STT/TTS only

Anyone passing per-call header overrides to STT or TTS specifically (createTranscription({ sttRequest, httpReferer: "..." })) will see a TS error — those headers must now be set on the OpenRouter constructor. In practice these are app-identification headers that almost always come from constructor options, not from per-call overrides, so the impact should be small.

Why an overlay (not a hand-written wrapper)

Hand-written wrappers around generated SDKs are explicitly disallowed for OpenRouter's generated SDKs. This change uses Speakeasy's own documented mechanism (x-speakeasy-globals-hidden) and is contained to a single overlay file.