Function draw_agent_identity_mark 

pub fn draw_agent_identity_mark(
    scene: &mut Scene,
    transform: Affine,
    rect: Rect,
    color: AlphaColor<Srgb>,
    theme: &Theme,
    style: AgentIdentityStyle,
)

Paint Tilo’s shared agent identity mark into rect.

color is the principal’s stable identity colour. The tile wears it, and the mark is inked as a person’s initials are on a face of the same colour (initial_ink): chosen through the active theme and tinted with the tile’s hue, so an agent beside a person reads at the same weight in every theme instead of wearing a fixed black or white glyph. The geometry scales down to the 9px live-presence badge without relying on a font or a UTF symbol.