improve(cli): surface AST parse errors during component validation

[MuhamadRifansyah]

Overview

Improve CLI validation diagnostics and lint hygiene without changing runtime behavior.

Changes

• Log parse failures in _check_class_in_dir to surface plugin syntax errors.
• Add module docstring, import guards for json5, and explicit UTF-8 file reads.
• Convert logging to lazy % formatting and add targeted lint suppressions for protected access and complexity warnings.
• Wrap long help text to satisfy linting.

Impact

More transparent validation errors and cleaner static-analysis output; no functional behavior changes.

ruff check

all passed

Additional Information

None.