App icon: just the fringe cube, no streamlines

The owner's final choice: the hex-meshed cube with its banded fringe,
drawn a little larger, with no streamlines at any size. The Icon Composer
document is back to the floor and cube groups.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

assets/app-icon/README.md

@@ -2,9 +2,7 @@
 
 FieldCraft's mark is a cube in isometric view, covered by a structured hexahedral mesh, whose
 faces carry a banded colour fringe (blue to red, hottest at the front corner) as a stress or
-temperature result would. Streamlines coloured by flow speed in the same bands, with arrowheads,
-sweep in from the lower left: two run into the top face and narrow into its mesh lines, so the
-flow becomes the structure, and one wraps around the cube. Its faces are separated by
+temperature result would. Its faces are separated by
 transparent gaps rather than painted edge lines, so the backdrop shows through them in every
 appearance. It is original artwork, attributed in `ATTRIBUTION.md`, and shares the Craft
 family's layout (rounded-square backdrop, isometric floor grid, lit top faces).
@@ -17,10 +15,10 @@ hand. It runs on macOS (sips, iconutil, `xcrun actool`) with ImageMagick (`magic
 | File | What it is |
 |---|---|
 | `icon.vectorcraft`, `icon.svg`, `icon.png` | The full icon on its backdrop, 1024 × 1024 |
-| `icon-small.vectorcraft`, `icon-small.svg`, `icon-small.png` | Small-size artwork used at 16–32 px: the fringe cube and one bold coloured streamline with an arrowhead, no mesh or floor grid, faces edge to edge |
+| `icon-small.vectorcraft`, `icon-small.svg`, `icon-small.png` | Small-size artwork used at 16–32 px: the fringe cube alone, no mesh or floor grid, faces edge to edge |
 | `icon.iconset/`, `icon.icns` | macOS iconset (sips) and its iconutil compilation |
 | `icon.ico` | Windows icon, 16–256 px |
-| `FieldCraft.icon/` | Icon Composer document: floor grid (Default and Dark), flow behind, cube (faces and mesh) and flow in front layers, each scaled to 90% |
+| `FieldCraft.icon/` | Icon Composer document: floor grid (Default and Dark), and cube (faces and mesh) layers, each scaled to 90% |
 | `layers/*.vectorcraft` | Editable sources of the Icon Composer layers |
 | `Assets.car` | `actool` compilation of `FieldCraft.icon` for macOS 26 and later (needs Xcode 26 or later; the task skips it with a note otherwise) |