refactor: 重构项目架构，拆分代码到模块化目录

将单文件tts_server.go重构为模块化项目结构，拆分出common、dto、middleware、router、controller、service、adapter、setting等目录，优化代码组织提升可维护性

dto/health.go

@@ -0,0 +1,31 @@
+package dto
+
+type HealthResponse struct {
+	Status       string                 `json:"status"`
+	Service      string                 `json:"service"`
+	Version      string                 `json:"version"`
+	Uptime       string                 `json:"uptime"`
+	StartTime    string                 `json:"start_time"`
+	Memory       map[string]interface{} `json:"memory"`
+	APIStats     APIStatsResponse       `json:"api_stats"`
+	Errors       ErrorResponse          `json:"errors"`
+	ConfigStatus ConfigStatusResponse   `json:"config_status"`
+}
+
+type APIStatsResponse struct {
+	TotalRequests         int       `json:"total_requests"`
+	SuccessfulRequests    int64     `json:"successful_requests"`
+	FailedRequests        int64     `json:"failed_requests"`
+	ErrorRatePercent      string    `json:"error_rate_percent"`
+	AvgResponseTimeMs     string    `json:"avg_response_time_ms"`
+	RecentResponseTimesMs []float64 `json:"recent_response_times_ms"`
+}
+
+type ErrorResponse struct {
+	RecentErrorsCount int `json:"recent_errors_count"`
+}
+
+type ConfigStatusResponse struct {
+	AllRequiredVarsSet bool `json:"all_required_vars_set"`
+	ConfigError        bool `json:"config_error"`
+}

dto/tts.go

@@ -0,0 +1,40 @@
+package dto
+
+import "time"
+
+type OpenAITTSRequest struct {
+	Model          string  `json:"model"`
+	Input          string  `json:"input"`
+	Voice          string  `json:"voice"`
+	ResponseFormat string  `json:"response_format,omitempty"`
+	Speed          float64 `json:"speed,omitempty"`
+}
+
+type V3TTSResponse struct {
+	ReqID    string   `json:"reqid"`
+	Code     int      `json:"code"`
+	Message  string   `json:"message"`
+	Event    string   `json:"event"`
+	Sequence int      `json:"sequence"`
+	Data     string   `json:"data"`
+	Sentence string   `json:"sentence,omitempty"`
+	IsFinal  bool     `json:"is_final"`
+	Usage    *V3Usage `json:"usage,omitempty"`
+}
+
+type V3Usage struct {
+	TextWords int `json:"text_words"`
+}
+
+type ByteDanceTTSConfig struct {
+	ApiKey     string
+	ResourceId string
+	Speaker    string
+	URL        string
+	Timeout    time.Duration
+}
+
+type SynthesisResult struct {
+	AudioData []byte
+	ReqID     string
+}