Support comments and blank lines inside ClassBlock

[pigpigyyy]

Motivation

• Class bodies previously could not contain standalone comments or preserved blank lines, causing formatting and compilation mismatches compared to table blocks; the change aims to make class blocks handle comments and empty lines like TableLit/TableBlock.

Description

• Extend the ClassBlock AST to accept YueComment_t and EmptyLine_t by updating ast_sel_list for ClassBlock in src/yuescript/yue_ast.h.
• Allow comment-only and empty-line+comment entries in the parser by updating the class_line rule in src/yuescript/yue_parser.cpp so it can parse (EmptyLine >> YueComment) and YueComment alternatives.
• Update formatting logic in ClassBlock_t::to_string in src/yuescript/yue_ast.cpp to print comment nodes with indentation and preserve empty lines, matching table block behavior.
• Accept YueComment_t and EmptyLine_t during class-body compilation traversal in src/yuescript/yue_compiler.cpp to avoid AST node mismatch errors.

Testing

• Ran make gen which builds the compiler and generates spec outputs; the build and generation completed successfully with make gen returning without error.

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Codex Task