Round commit graph connections

TESTING.md

@@ -196,8 +196,9 @@ xcrun simctl launch booted de.rfc1437.gotcha
       All in the navigation bar, and includes commits from multiple branches.
 - [ ] Open the branch menu; All is checked. Select a branch and verify the label,
       checkmark, commits, and graph update, then return to All.
-- [ ] Commit graph lanes and merge connections align with their rows while
-      scrolling.
+- [ ] Commit graph lanes align with their rows while scrolling; branch-out and
+      merge-back connections use smooth, rounded curves that meet the correct
+      lane and commit node without angular horizontal bars or overlaps.
 - [ ] Open a commit and verify Changed Files paths and statuses.
 - [ ] Open a changed file and verify the diff title, old/new line numbers,
       monospaced text, addition/removal/hunk colors, vertical scrolling, and