feat(swagger): support dynamic host via EZ_SWAGGER_HOST env var

- Add ServerConfig.SwaggerHost field
- Set docs.SwaggerInfo.Host dynamically at startup
- Update docker-compose, k8s manifests, and .env.example

internal/config/config.go

@@ -23,7 +23,8 @@ type Config struct {
 }
 
 type ServerConfig struct {
-	Port string
+	Port        string
+	SwaggerHost string // Swagger UI 显示的 Host (可选，留空则使用相对路径)
 }
 
 type CORSConfig struct {
@@ -83,6 +84,7 @@ func Load() (*Config, error) {
 	v := viper.New()
 
 	v.SetDefault("server.port", "8080")
+	v.SetDefault("server.swagger_host", "")
 	v.SetDefault("cors.allow_origins", "*")
 	v.SetDefault("postgres.dsn", "host=localhost user=postgres password=postgres dbname=ezapi port=5432 sslmode=disable")
 	v.SetDefault("redis.addr", "localhost:6379")
@@ -114,6 +116,7 @@ func Load() (*Config, error) {
 	v.AutomaticEnv()
 
 	_ = v.BindEnv("server.port", "EZ_API_PORT")
+	_ = v.BindEnv("server.swagger_host", "EZ_SWAGGER_HOST")
 	_ = v.BindEnv("cors.allow_origins", "EZ_CORS_ALLOW_ORIGINS")
 	_ = v.BindEnv("postgres.dsn", "EZ_PG_DSN")
 	_ = v.BindEnv("redis.addr", "EZ_REDIS_ADDR")
@@ -158,7 +161,8 @@ func Load() (*Config, error) {
 
 	cfg := &Config{
 		Server: ServerConfig{
-			Port: v.GetString("server.port"),
+			Port:        v.GetString("server.port"),
+			SwaggerHost: strings.TrimSpace(v.GetString("server.swagger_host")),
 		},
 		CORS: CORSConfig{
 			AllowOrigins: splitCommaList(v.GetString("cors.allow_origins")),