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>

model/custom_types/auto_json.go

@@ -7,7 +7,7 @@ import (
 	"fmt"
 )
 
-// AutoJson 数据类型
+// AutoJson data type
 type AutoJson json.RawMessage
 
 func (j *AutoJson) Scan(value interface{}) error {
@@ -33,7 +33,7 @@ func (j *AutoJson) Scan(value interface{}) error {
 	}
 	result := &json.RawMessage{}
 	err := json.Unmarshal(bytes, result)
-	//解析json错误 返回空
+	// json parse error, return empty
 	if err != nil {
 		*j = AutoJson(json.RawMessage{'[', ']'})
 		return nil

model/custom_types/auto_time.go

@@ -5,7 +5,7 @@ import (
 	"time"
 )
 
-// AutoTime 自定义时间格式
+// AutoTime custom time format
 type AutoTime time.Time
 
 func (mt AutoTime) Value() (driver.Value, error) {