site, branding: skeuomorphic marks, and the new Niveus components

The marks are now drawn the way Niveus draws its keys: one light from the
upper left, gloss on the faces that catch it, a specular line on the edges
that face it, and soft contact shadows.

- Shift: shaded slabs, each casting onto the one below. shift-mask.svg is
  untouched, so the kernel's logo.h coverage mask is unchanged.
- Uberblock: bevelled slots in a groove; the newest slot and the root glow.
- USB stick: moulded body, steel connector, a lit activity LED.
- Pride flag: cloth folds and a hem over the flag's own colours.

The pages use the components the new Niveus added: both terminals are
.nv-window frames, the origin and first-boot sequences are .nv-steps, the
numbers are a .nv-stat-group, and each feature card has an .nv-tile glyph.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S1giNvrHTrPMPw7V6x1kQ4

docs/branding/README.md

@@ -57,6 +57,12 @@ the kernel's name (**SchIFT**) as a shape.
 - **With or without a wordmark.** Set "SchOS" beside it in **Roboto Bold**,
   which is already in the tree (`ports/Roboto`), Apache-2.0, and already
   in `NOTICE`.
+- **Rendered as an object, drawn as a shape.** The colour `shift.svg` is lit
+  the way Niveus lights a key -- one light from the upper left, a gloss across
+  each top face, a specular line on the edges that face it, and a soft shadow
+  from each slab onto the next. None of that is in the silhouette:
+  `shift-mask.svg` is the same geometry with no shading, and it is still what
+  `include/gfx/logo.h` is built from, so the kernel's mark is unchanged.
 - Non-human and non-animal, permanently. If a character is ever drawn it gets
   its own mark; a logo that starts growing a face has taken that job.