downloads: store deb + Windows msi/zip as Git LFS

Big binaries as plain blobs made Gitea show 'too large' and refuse to
download on click. Track *.msi/*.zip/*.deb/*.exe with Git LFS so the files
stay visible in the repo root AND download with a working button, any size.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitattributes

@@ -1 +1,5 @@
 *.sh text eol=lf
+*.msi filter=lfs diff=lfs merge=lfs -text
+*.zip filter=lfs diff=lfs merge=lfs -text
+*.deb filter=lfs diff=lfs merge=lfs -text
+*.exe filter=lfs diff=lfs merge=lfs -text