v1.8.0: Audio 代码重构与低功耗优化 (#943)

* Reconstruct Audio Code

* Remove old IoT implementation

* Add MQTT-UDP documentation

* OTA升级失败时，可以继续使用

main/audio/wake_words/esp_wake_word.h

@@ -0,0 +1,48 @@
+#ifndef ESP_WAKE_WORD_H
+#define ESP_WAKE_WORD_H
+
+#include <freertos/FreeRTOS.h>
+#include <freertos/task.h>
+#include <freertos/event_groups.h>
+
+#include <esp_wn_iface.h>
+#include <esp_wn_models.h>
+#include <model_path.h>
+
+#include <list>
+#include <string>
+#include <vector>
+#include <functional>
+#include <mutex>
+#include <condition_variable>
+
+#include "audio_codec.h"
+#include "wake_word.h"
+
+class EspWakeWord : public WakeWord {
+public:
+    EspWakeWord();
+    ~EspWakeWord();
+
+    void Initialize(AudioCodec* codec);
+    void Feed(const std::vector<int16_t>& data);
+    void OnWakeWordDetected(std::function<void(const std::string& wake_word)> callback);
+    void Start();
+    void Stop();
+    size_t GetFeedSize();
+    void EncodeWakeWordData();
+    bool GetWakeWordOpus(std::vector<uint8_t>& opus);
+    const std::string& GetLastDetectedWakeWord() const { return last_detected_wake_word_; }
+
+private:
+    esp_wn_iface_t *wakenet_iface_ = nullptr;
+    model_iface_data_t *wakenet_data_ = nullptr;
+    srmodel_list_t *wakenet_model_ = nullptr;
+    EventGroupHandle_t event_group_;
+    AudioCodec* codec_ = nullptr;
+
+    std::function<void(const std::string& wake_word)> wake_word_detected_callback_;
+    std::string last_detected_wake_word_;
+};
+
+#endif