[djl11]

Follows #27 onto the diagrams. On 29 September the flat mark became the logo, and the colour mark now sits only on one solid brand colour, never a gradient (unifyai/branding f8ce731, d38d6d5). The diagrams still carried the lit mark from #26, and on dark over a peach-to-mauve wash in the corner.

• The 44 diagram PNGs are re-rendered from branding 213673e at the same size and file name, so every README that links here, including unify-agent's docs, updates without an edit. The badge is the flat mark (solid aqua and coral, ink lens on haze, cream on midnight) straight on the ground, and the dark corner wash is gone. Colour by role is unchanged.
• The README hero is regenerated through the image-model path in branding's docs-diagrams pipeline, light and dark, with the flat mark and a plain midnight ground. Every label was read against the layout spec.
• The mark and banners already went over in Show the flat mark in the README banners and mark #27; this leaves them alone.