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>

lib/cache/redis_test.go

@@ -17,7 +17,7 @@ func TestRedisSet(t *testing.T) {
 	err := rc.Set("123", "ddd", 0)
 	if err != nil {
 		fmt.Println(err.Error())
-		t.Fatalf("写入失败")
+		t.Fatalf("write failed")
 	}
 }
 
@@ -29,12 +29,12 @@ func TestRedisGet(t *testing.T) {
 	})
 	err := rc.Set("123", "451156", 300)
 	if err != nil {
-		t.Fatalf("写入失败")
+		t.Fatalf("write failed")
 	}
 	res := ""
 	err = rc.Get("123", &res)
 	if err != nil {
-		t.Fatalf("读取失败")
+		t.Fatalf("read failed")
 	}
 	fmt.Println("res", res)
 }
@@ -54,16 +54,16 @@ func TestRedisGetJson(t *testing.T) {
 	}
 	err := rc.Set("1233", old, 300)
 	if err != nil {
-		t.Fatalf("写入失败")
+		t.Fatalf("write failed")
 	}
 
 	res := &r{}
 	err2 := rc.Get("1233", res)
 	if err2 != nil {
-		t.Fatalf("读取失败")
+		t.Fatalf("read failed")
 	}
 	if !reflect.DeepEqual(res, old) {
-		t.Fatalf("读取错误")
+		t.Fatalf("read error")
 	}
 	fmt.Println(res, res.Aa)
 }