Here's the direction I took:

• Mark: A single rotated square with one corner shaved flat — a card on edge, abstracted until it reads as a symbol
• Palette: A cool steel-blue accent (#2F7A9E) laid over a near-black ink field (#131519)
• Style: Flat, hard-edged, wide margins, no lettering and no gradients

The mark is already written to resources/branding/appmark.iconset/mark@3x.png and will be picked up on your next build. Want me to run a build to confirm everything still compiles?