Function render_inline 

pub fn render_inline(
    image_b64: &str,
    mime_type: &str,
    max_cols: usize,
) -> String

Render an image for inline terminal display.

• image_b64: base64-encoded image data (as stored in ImageContent.data).
• mime_type: MIME type string (e.g. "image/png").
• max_cols: maximum display width in terminal columns.

Returns the string to write to the terminal.

Note: today this always returns a plain-text placeholder (see module docs).