README opens with a hero image showing all seven directions, light and dark

[escherlies]

Kind: feature request

Current behaviour

The README introduces the library's seven directions only as a text table of
names and one-line ideas (README.md:11-19), followed by a link to the hosted
demo (README.md:21). It contains no image markup of any kind — no ![…], no
<img>, no <picture> — and the repo tracks no image assets at all
(git ls-files matches no .png/.jpg/.svg/.webp/.gif). A reader on
github.com therefore cannot see what any of the seven surfaces looks like
without leaving the page for the demo, and cannot see them at all offline or
if the demo link is unavailable. Nothing here touches authentication,
authorization, secrets, or user data.

Desired outcome

The README opens with a hero image that shows all seven directions, in a light
variant and a dark variant that follow the reader's own theme.

Done when

The top of README.md renders a hero image on github.com in which each of the
seven directions in SURFACES (src/surfaces/registry.ts:36-125) is visible,
the image swaps between a light and a dark version with the viewer's theme,
and the repo's declared gate for a change still passes (mise run check, per
AGENTS.md "Stack & commands").

Out of scope

• Changing how any surface renders in order to make it photograph well — the
  image documents the library at HEAD, it does not drive it.
• Replacing the hosted demo link (README.md:21); the image is in addition to
  it, not instead of it.