refactor/code-improvements

[indaco]

Summary

• Bumped Go version and updated dependencies.
• Added development tooling and enabled changelog-generator plugin.
• Introduced a validation package for input sanitization.
• Improved worker concurrency safety and resource cleanup.
• Added interfaces for dependency injection.
• Reorganized helpers package and added documentation.
• Reduced cyclomatic complexity in config.
• Added compatibility tests for errors.Is and errors.As.
• Updated CI actions to latest versions and bumped Go to v1.25.