Skip redundant line-number comments on empty lines

[pigpigyyy]

Motivation

• The compiler emitted standalone trailing line-number comments (e.g. -- 123) for EmptyLine_t nodes inside tablelit, tableblock and classblock when reserve_line_number/-l was enabled, producing redundant comment-only lines in generated output.

Description

• Update nl(ast_node* node) in src/yuescript/yue_compiler.cpp to return only the newline for EmptyLine_t nodes when _config.reserveLineNumber is true, avoiding the -- <line> suffix for blank lines.
• Add a regression CLI test in spec/cli/test_compilation.sh that compiles a file containing empty lines inside table/class blocks and asserts no standalone -- <number> lines are present.
• Modified files: src/yuescript/yue_compiler.cpp and spec/cli/test_compilation.sh.

Testing

• Built the project with make -j4 and the build completed successfully.
• Ran the CLI tests with YUE_BIN=./yue spec/cli/test_compilation.sh and all tests passed (21/21), including the new regression asserting empty lines do not produce standalone line-number comment lines.

---

Codex Task