Document Git LFS tracking for binary assets (HF requires LFS)

.gitattributes

@@ -1,5 +1,5 @@
-# LUNA.png (~2.4MB) and the demo .mp4 (~0.9MB) are small enough to commit directly.
-# They are intentionally NOT tracked by Git LFS so the deployed Space always has the
-# real binaries (an un-pushed LFS object would otherwise show a broken image).
+# Binary assets (LUNA.png, the demo .mp4) are stored via Git LFS — the
+# Hugging Face Space requires binaries to go through LFS/Xet rather than raw
+# git blobs. The real LFS objects are pushed so the Space serves the actual files.
 *.png filter=lfs diff=lfs merge=lfs -text
 *.mp4 filter=lfs diff=lfs merge=lfs -text