feat(git): set difft as diff application if available

zsh/git.zsh

@@ -5,9 +5,19 @@
 # Stolen from: https://stackoverflow.com/a/42544963
 git-largest-objects() {
   git rev-list --objects --all |
-    git cat-file --batch-check='%(objecttype) %(objectname) %(objectsize) %(rest)' |
+    git cat-file \
+      --batch-check='%(objecttype) %(objectname) %(objectsize) %(rest)' |
     sed -n 's/^blob //p' |
     sort --numeric-sort --key=2 |
     cut -c 1-12,41- |
-    $(command -v gnumfmt || echo numfmt) --field=2 --to=iec-i --suffix=B --padding=7 --round=nearest
+    $(command -v gnumfmt || echo numfmt) \
+      --field=2 \
+      --to=iec-i \
+      --suffix=B \
+      --padding=7 \
+      --round=nearest
 }
+
+if command-exists difft; then
+  export GIT_EXTERNAL_DIFF=difft
+fi