Function format_timing 

pub(crate) fn format_timing(duration: Duration) -> String

Format lint duration into time=<duration> snippet (auto-scaled, no color).

Note: Colorization (if any) is applied by the caller (e.g. in report) not here, keeping this helper suitable for future machine-readable output modes.

Rationale

• Improves readability vs raw integer milliseconds; preserves sub-ms precision.
• Uses stable standard library formatting (no custom scaling logic).