Function format_log_event_line 

pub fn format_log_event_line(
    server_id: Option<&str>,
    level: &str,
    source: &str,
    message: &str,
) -> String

Format one log record line for append to a synthetic LSP log buffer (B’.3: hoisted out of lattice_ui_tui::app::lsp_log_buffers so log modes in this crate can reuse it from a tokio task). Shape: HH:MM:SS.mmm [<server>] <level> <source>: <message>. Trailing newline is the caller’s responsibility (the drain batches many records into one buffer-append).