refactor(api-client): publish only the shared contract from the root barrel

packages/api-client/src/stt-contract.ts

@@ -0,0 +1,22 @@
+// packages/api-client/src/stt-contract.ts
+// Cloud STT gateway(Supabase Edge `stt-proxy`) 요청/응답 계약 타입.
+// 런타임 호출 코드는 각 앱이 소유하고, 이 모듈은 타입 계약만 공유한다.
+
+export interface TranscribeAudioParams {
+  audio: Blob | ArrayBuffer | Uint8Array | string
+  language?: string
+  supabaseUrl?: string
+  anonKey?: string
+  token?: string
+}
+
+export interface TranscribeAudioResult {
+  text: string
+  confidence: number
+  language: string
+  durationSeconds: number
+  provider: string
+  latencyMs: number
+  modelId?: string
+  cost?: number
+}