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/cache_test.go

@@ -42,7 +42,7 @@ func TestFileCacheSet(t *testing.T) {
 	err := fc.Set("123", "ddd", 0)
 	if err != nil {
 		fmt.Println(err.Error())
-		t.Fatalf("写入失败")
+		t.Fatalf("write failed")
 	}
 }
 
@@ -50,12 +50,12 @@ func TestFileCacheGet(t *testing.T) {
 	fc := New("file")
 	err := fc.Set("123", "45156", 300)
 	if err != nil {
-		t.Fatalf("写入失败")
+		t.Fatalf("write failed")
 	}
 	res := ""
 	err = fc.Get("123", &res)
 	if err != nil {
-		t.Fatalf("读取失败")
+		t.Fatalf("read failed")
 	}
 	fmt.Println("res", res)
 }
@@ -69,7 +69,7 @@ func TestRedisCacheSet(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")
 	}
 }
 
@@ -81,12 +81,12 @@ func TestRedisCacheGet(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)
 }