Fix clippy pedantic and nursery warnings

[frisoft]

Summary

• Updated CI workflow to enable clippy::pedantic and clippy::nursery lints
• Applied various code style fixes to satisfy stricter linting:
  • Converted functions to const fn where possible
  • Replaced match with map_or_else for better style
  • Added necessary #[allow(...)] attributes
  • Used Self instead of type name in impl blocks

[frisoft]

Not sure about the changes.