NOTEPAD: close the CubeLoader bug, note the loader the portal now draws

The invisible loader lived in the index repo only and is fixed there. What is
left for this repo is whether its lucide spinners should become the same brand
mark.

NOTEPAD.md

@@ -144,7 +144,7 @@ Deferring because out of scope is fine, but don't mention deferring than.
   it. Nothing exercises Python 3.13/3.14 in CI — the matrix is one version.
 
 - BUG/UI assimilate the design of the settings in the app to mirror the design of the settings in the portal
-- BUG/UI: `CubeLoader` (`index/frontend/src/components/ui/cube-loader.tsx`; the index repo only, nothing in `app/` references it) paints nothing. Its `<path>` carries `className="n3xd-cube-line"` and the header comment points at that rule plus `n3xd-build-cube` keyframes "in index.css" — neither exists in `frontend/src/index.css` (nor in the index repo, which has the same component). Every pending state using it shows an invisible SVG. Related to the global loading animation below.
+- CHORE/UI: pending states here are lucide's `Loader2` on `animate-spin`; the portal draws the brand mark instead (`index/frontend/src/components/ui/fluksio-loader.tsx` plus the `.fluksio-loader-line` rule at the foot of its `index.css`). Copying both across — the shadcn model, so the CSS travels with the component — would make one loading mark across the two shells.
 - CHORE/INFRA: the `generate-frontend-sdk` pre-commit hook runs `scripts/generate-client.sh`
   on any `backend/**` change, and that script ends by formatting the whole frontend tree —
   while `biome.json` excludes `src/client`, so it formats nothing the generator wrote. Every