i18n: Translate all Chinese to English across the codebase

Translate Chinese comments, log/error messages, validator labels and
Swagger annotations to English throughout the source code, generated
Swagger docs, config files and CI workflows.

Make the English README primary: README.md now holds the English docs
and README_EN.md holds the Chinese version, with cross-language links
updated accordingly.

Note: the generated docs/ swagger files were translated in place; run
`go generate ./...` (swag init) to regenerate them from the now-English
annotations when a Go toolchain is available.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

http/middleware/logger.go

@@ -6,7 +6,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
-// Logger 日志中间件
+// Logger logging middleware
 func Logger() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		global.Logger.WithFields(