refactor: 重构配置结构，解耦热词、统一认证、移除 TLS 开关

- 新增 ASRConfig，热词从 doubao 提升为 provider 无关配置
- 移除 SecurityConfig，token 移入 ServerConfig
- 移除 tls_auto 配置项，TLS 始终启用（getUserMedia 要求 HTTPS）
- validate() 改为基于 provider 白名单验证，增加 resource_id 校验
- 简化 main.go：移除 scheme 变量和 HTTP 降级分支
- 更新 config.example.yaml 为新结构并修正环境变量前缀

internal/config/config.go

@@ -7,45 +7,48 @@ import (
 	"strings"
 	"sync"
 	"sync/atomic"
+
 	"github.com/fsnotify/fsnotify"
 	"github.com/spf13/viper"
 )
 
-// DoubaoConfig holds 火山引擎豆包 ASR credentials.
-type DoubaoConfig struct {
-	AppID       string   `mapstructure:"app_id"`
-	AccessToken string   `mapstructure:"access_token"`
-	ResourceID  string   `mapstructure:"resource_id"`
-	Hotwords    []string `mapstructure:"hotwords"` // 本地热词列表
+// ASRConfig holds ASR settings independent of any specific provider.
+type ASRConfig struct {
+	Provider string   `mapstructure:"provider"`
+	Hotwords []string `mapstructure:"hotwords"` // 通用热词列表
 }
 
-// SecurityConfig holds authentication settings.
-type SecurityConfig struct {
-	Token string `mapstructure:"token"`
+// DoubaoConfig holds 火山引擎豆包 ASR credentials.
+type DoubaoConfig struct {
+	AppID       string `mapstructure:"app_id"`
+	AccessToken string `mapstructure:"access_token"`
+	ResourceID  string `mapstructure:"resource_id"`
 }
 
 // ServerConfig holds server settings.
 type ServerConfig struct {
-	Port    int  `mapstructure:"port"`
-	TLSAuto bool `mapstructure:"tls_auto"`
+	Port  int    `mapstructure:"port"`
+	Token string `mapstructure:"token"`
 }
 
 // Config is the top-level configuration.
 type Config struct {
-	Doubao   DoubaoConfig   `mapstructure:"doubao"`
-	Server   ServerConfig   `mapstructure:"server"`
-	Security SecurityConfig `mapstructure:"security"`
+	ASR    ASRConfig    `mapstructure:"asr"`
+	Doubao DoubaoConfig `mapstructure:"doubao"`
+	Server ServerConfig `mapstructure:"server"`
 }
 
 // defaults returns a Config with default values.
 func defaults() Config {
 	return Config{
+		ASR: ASRConfig{
+			Provider: "doubao",
+		},
 		Doubao: DoubaoConfig{
 			ResourceID: "volc.seedasr.sauc.duration",
 		},
 		Server: ServerConfig{
-			Port:    8443,
-			TLSAuto: true,
+			Port: 8443,
 		},
 	}
 }
@@ -70,9 +73,9 @@ func Load(path string) (Config, error) {
 
 	// Set defaults
 	def := defaults()
+	v.SetDefault("asr.provider", def.ASR.Provider)
 	v.SetDefault("doubao.resource_id", def.Doubao.ResourceID)
 	v.SetDefault("server.port", def.Server.Port)
-	v.SetDefault("server.tls_auto", def.Server.TLSAuto)
 
 	// Allow env var overrides (e.g., VOICEPASTE_DOUBAO_APP_ID)
 	v.SetEnvPrefix("voicepaste")
@@ -98,13 +101,23 @@ func Load(path string) (Config, error) {
 	store(cfg)
 	return cfg, nil
 }
-// validate checks required fields.
+
+// validate checks required fields based on the configured ASR provider.
 func validate(cfg Config) error {
-	if cfg.Doubao.AppID == "" {
-		return fmt.Errorf("doubao.app_id is required")
-	}
-	if cfg.Doubao.AccessToken == "" {
-		return fmt.Errorf("doubao.access_token is required")
+	provider := strings.TrimSpace(strings.ToLower(cfg.ASR.Provider))
+	switch provider {
+	case "doubao":
+		if cfg.Doubao.AppID == "" {
+			return fmt.Errorf("doubao.app_id is required when asr.provider is \"doubao\"")
+		}
+		if cfg.Doubao.AccessToken == "" {
+			return fmt.Errorf("doubao.access_token is required when asr.provider is \"doubao\"")
+		}
+		if cfg.Doubao.ResourceID == "" {
+			return fmt.Errorf("doubao.resource_id is required when asr.provider is \"doubao\"")
+		}
+	default:
+		return fmt.Errorf("unsupported asr.provider: %q (supported: doubao)", cfg.ASR.Provider)
 	}
 	return nil
 }
@@ -170,9 +183,9 @@ func WatchAndReload(path string) func() {
 	v.SetConfigType("yaml")
 	// Set defaults
 	def := defaults()
+	v.SetDefault("asr.provider", def.ASR.Provider)
 	v.SetDefault("doubao.resource_id", def.Doubao.ResourceID)
 	v.SetDefault("server.port", def.Server.Port)
-	v.SetDefault("server.tls_auto", def.Server.TLSAuto)
 	v.SetEnvPrefix("voicepaste")
 	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	v.AutomaticEnv()
@@ -247,8 +260,8 @@ func Get() Config {
 	if v := global.Load(); v != nil {
 		cfg := v.(Config)
 		// Deep copy hotwords slice to prevent external modifications
-		if cfg.Doubao.Hotwords != nil {
-			cfg.Doubao.Hotwords = append([]string(nil), cfg.Doubao.Hotwords...)
+		if cfg.ASR.Hotwords != nil {
+			cfg.ASR.Hotwords = append([]string(nil), cfg.ASR.Hotwords...)
 		}
 		return cfg
 	}
@@ -259,8 +272,8 @@ func Get() Config {
 // Deep copies slices to ensure immutability.
 func store(cfg Config) {
 	// Deep copy hotwords to prevent external modifications
-	if cfg.Doubao.Hotwords != nil {
-		cfg.Doubao.Hotwords = append([]string(nil), cfg.Doubao.Hotwords...)
+	if cfg.ASR.Hotwords != nil {
+		cfg.ASR.Hotwords = append([]string(nil), cfg.ASR.Hotwords...)
 	}
 	global.Store(cfg)
 }