refactor(bodylimit): 将 FormatSize 改为私有函数 formatSize

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

internal/middleware/bodylimit/bodylimit.go

@@ -279,7 +279,7 @@ func ParseSize(sizeStr string) (int64, error) {
 //
 // 返回值：
 //   - string: 格式化后的字符串，如 "1mb", "10kb" 等
-func FormatSize(size int64) string {
+func formatSize(size int64) string {
 	const (
 		KB = 1024
 		MB = 1024 * KB

internal/middleware/bodylimit/bodylimit_test.go

@@ -62,10 +62,10 @@ func TestFormatSize(t *testing.T) {
 	}
 
 	for _, tt := range tests {
-		t.Run(FormatSize(tt.input), func(t *testing.T) {
-			got := FormatSize(tt.input)
+		t.Run(formatSize(tt.input), func(t *testing.T) {
+			got := formatSize(tt.input)
 			if got != tt.expected {
-				t.Errorf("FormatSize(%d) = %s, want %s", tt.input, got, tt.expected)
+				t.Errorf("formatSize(%d) = %s, want %s", tt.input, got, tt.expected)
 			}
 		})
 	}