add comprehensive javadoc comments for all classes

- Add class-level documentation for all mapper and multilingual classes
- Add complete javadoc for all public methods with @param and @return tags
- Add field-level comments for better code readability
- Improve documentation for initialization blocks and constructors

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

src/main/java/com/imyeyu/lang/mapper/FileLanguageMap.java

@@ -8,6 +8,8 @@ import java.io.InputStreamReader;
 import java.util.Properties;
 
 /**
+ * 文件语言映射
+ *
  * @author 夜雨
  * @version 2024-04-09 01:00
  */
@@ -22,6 +24,11 @@ public class FileLanguageMap extends PropertiesLanguageMap {
 		super(language);
 	}
 
+	/**
+	 * 加载资源文件，格式化 % 为 {@link Language.Enum#toString()}，示例：lang/app_%s.lang
+	 *
+	 * @param path 路径
+	 */
 	public void load(String path) {
 		try {
 			InputStream is = IO.getInputStream(path.formatted(language.toString()));