add-javadoc（添加 javadoc）

Add comprehensive JavaDoc documentation to all public classes and methods.

Class-Level Documentation

For each public class:

• Add class-level JavaDoc describing the purpose and responsibility of the class
• Include @author tag if appropriate

Method-Level Documentation

For each public method:

• Add method-level JavaDoc describing what the method does
• Include @param tags for all parameters with clear descriptions
• Include @return tag describing the return value
• Include @throws tags for any checked exceptions

Style Guidelines

• First sentence should be a concise summary
• Use HTML tags sparingly (prefer plain text)
• Document preconditions and postconditions when relevant
• Include code examples with {@code...} for complex methods

See references/example.md for before/after examples.