README: add sibling link back to daedalus-fourier

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

README.md

@@ -10,6 +10,10 @@ implementation not yet begun.
 
 ## What this is
 
+Sibling repo to
+[daedalus-fourier](https://git.reauktion.de/marfrit/daedalus-fourier)
+(the kernel library; cycles 1-9 closed).
+
 A two-piece userspace + kernel-module stack that exposes a V4L2
 stateless decoder interface (`/dev/videoNN`) so that
 `libva-v4l2-request-fourier` → `firefox-fourier` /