M7: README: ArtCraft logo from a public URL so it loads in every client (#57)

This repository is private, so clients that show the README without the
viewer's GitHub session (the GitHub mobile app, link previews) can't fetch
images stored here, and the ArtCraft logo showed as a broken image. Load
the identical logo and mark from the public VectorCraft repository
instead, the same files every Crafting App ships.

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -1,8 +1,8 @@
 <p align="center">
   <a href="https://getartcraft.com/">
     <picture>
-      <source media="(prefers-color-scheme: dark)" srcset="docs/brand/artcraft-logo-white.png">
-      <img alt="ArtCraft" src="docs/brand/artcraft-logo.png" width="200">
+      <source media="(prefers-color-scheme: dark)" srcset="https://raw.githubusercontent.com/storytold/vectorcraft/main/docs/brand/artcraft-logo-white.png">
+      <img alt="ArtCraft" src="https://raw.githubusercontent.com/storytold/vectorcraft/main/docs/brand/artcraft-logo.png" width="200">
     </picture>
   </a>
 </p>
@@ -227,7 +227,7 @@ Forks and modified versions must remove them.
 <sub>Figma is a trademark of Figma, Inc. FigCraft is an independent, open-source project and is not affiliated with, sponsored by or endorsed by Figma, Inc.; the name is used only to describe the workflows FigCraft is compatible with.</sub>
 
 <p align="center">
-  <a href="https://getartcraft.com/"><img alt="ArtCraft" src="docs/brand/artcraft-mark.png" width="28"></a><br>
+  <a href="https://getartcraft.com/"><img alt="ArtCraft" src="https://raw.githubusercontent.com/storytold/vectorcraft/main/docs/brand/artcraft-mark.png" width="28"></a><br>
   <sub>Made by the <a href="https://getartcraft.com/">ArtCraft</a> team and community.</sub>
 </p>