feat: add Voxtral WebSocket message types and parser

MyVoxtral/MyVoxtral/Network/VoxtralMessages.swift

@@ -0,0 +1,123 @@
+import Foundation
+
+// MARK: - Outbound Messages (Client → Server)
+
+struct AudioAppendMessage: Encodable {
+    let type = "input_audio.append"
+    let audio: String // base64-encoded PCM
+}
+
+struct AudioFlushMessage: Encodable {
+    let type = "input_audio.flush"
+}
+
+struct AudioEndMessage: Encodable {
+    let type = "input_audio.end"
+}
+
+struct SessionUpdateMessage: Encodable {
+    let type = "session.update"
+    let session: SessionConfig
+}
+
+struct SessionConfig: Encodable {
+    let audioFormat: AudioFormatConfig
+    let targetStreamingDelayMs: Int
+
+    enum CodingKeys: String, CodingKey {
+        case audioFormat = "audio_format"
+        case targetStreamingDelayMs = "target_streaming_delay_ms"
+    }
+}
+
+struct AudioFormatConfig: Encodable {
+    let encoding = "pcm_s16le"
+    let sampleRate = 16000
+
+    enum CodingKeys: String, CodingKey {
+        case encoding
+        case sampleRate = "sample_rate"
+    }
+}
+
+// MARK: - Inbound Messages (Server → Client)
+
+enum VoxtralEvent {
+    case sessionCreated
+    case textDelta(String)
+    case segment(text: String, start: Double, end: Double)
+    case language(String)
+    case done(text: String)
+    case error(String)
+    case unknown(String)
+}
+
+struct IncomingEvent: Decodable {
+    let type: String
+}
+
+struct TextDeltaEvent: Decodable {
+    let text: String
+}
+
+struct LanguageEvent: Decodable {
+    let audioLanguage: String
+
+    enum CodingKeys: String, CodingKey {
+        case audioLanguage = "audio_language"
+    }
+}
+
+struct SegmentEvent: Decodable {
+    let text: String
+    let start: Double
+    let end: Double
+}
+
+struct DoneEvent: Decodable {
+    let text: String
+}
+
+struct ErrorEvent: Decodable {
+    let error: ErrorDetail?
+}
+
+struct ErrorDetail: Decodable {
+    let message: ErrorMessage?
+}
+
+struct ErrorMessage: Decodable {
+    let detail: String?
+}
+
+// MARK: - Event Parsing
+
+func parseVoxtralEvent(from data: Data) -> VoxtralEvent {
+    guard let envelope = try? JSONDecoder().decode(IncomingEvent.self, from: data) else {
+        return .unknown(String(data: data, encoding: .utf8) ?? "")
+    }
+
+    switch envelope.type {
+    case "session.created":
+        return .sessionCreated
+    case "transcription.text.delta":
+        guard let e = try? JSONDecoder().decode(TextDeltaEvent.self, from: data) else { return .unknown("") }
+        return .textDelta(e.text)
+    case "transcription.segment":
+        guard let e = try? JSONDecoder().decode(SegmentEvent.self, from: data) else { return .unknown("") }
+        return .segment(text: e.text, start: e.start, end: e.end)
+    case "transcription.language":
+        guard let e = try? JSONDecoder().decode(LanguageEvent.self, from: data) else { return .unknown("") }
+        return .language(e.audioLanguage)
+    case "transcription.done":
+        guard let e = try? JSONDecoder().decode(DoneEvent.self, from: data) else { return .unknown("") }
+        return .done(text: e.text)
+    case "error":
+        if let e = try? JSONDecoder().decode(ErrorEvent.self, from: data) {
+            return .error(e.error?.message?.detail ?? "Unknown error")
+        }
+        return .error("Unknown error")
+    default:
+        return .unknown(envelope.type)
+    }
+}