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/processors/no_audio_processor.cc

@@ -0,0 +1,50 @@
+#include "no_audio_processor.h"
+#include <esp_log.h>
+
+#define TAG "NoAudioProcessor"
+
+void NoAudioProcessor::Initialize(AudioCodec* codec) {
+    codec_ = codec;
+}
+
+void NoAudioProcessor::Feed(const std::vector<int16_t>& data) {
+    if (!is_running_ || !output_callback_) {
+        return;
+    }
+    // 直接将输入数据传递给输出回调
+    output_callback_(std::vector<int16_t>(data));
+}
+
+void NoAudioProcessor::Start() {
+    is_running_ = true;
+}
+
+void NoAudioProcessor::Stop() {
+    is_running_ = false;
+}
+
+bool NoAudioProcessor::IsRunning() {
+    return is_running_;
+}
+
+void NoAudioProcessor::OnOutput(std::function<void(std::vector<int16_t>&& data)> callback) {
+    output_callback_ = callback;
+}
+
+void NoAudioProcessor::OnVadStateChange(std::function<void(bool speaking)> callback) {
+    vad_state_change_callback_ = callback;
+}
+
+size_t NoAudioProcessor::GetFeedSize() {
+    if (!codec_) {
+        return 0;
+    }
+    // 返回一个固定的帧大小，比如 30ms 的数据
+    return 30 * codec_->input_sample_rate() / 1000;
+}
+
+void NoAudioProcessor::EnableDeviceAec(bool enable) {
+    if (enable) {
+        ESP_LOGE(TAG, "Device AEC is not supported");
+    }
+}