Function render 

pub fn render(
    diagnostics: &[Diagnostic],
    filename: &str,
    source: &str,
) -> String

Render a slice of diagnostics to a string using ariadne for source context.

filename and source must correspond to the file referenced by the diagnostics’ spans. This function is intentionally decoupled from bock-source types so that bock-errors stays dependency-free.

Color is decided automatically via color_enabled_for_diagnostics: ANSI escapes are emitted only when stderr is an interactive terminal and NO_COLOR is unset. Use render_with_color to force the decision.