Show commit details above changed files

TESTING.md

@@ -217,7 +217,11 @@ xcrun simctl launch booted de.rfc1437.gotcha
 - [ ] In **All** history, branch names use the accent color both at branch tips
       and at the first commit made on a pull-request branch, including a merged
       branch whose tip was deleted.
-- [ ] Open a commit and verify Changed Files paths and statuses.
+- [ ] Open a commit and verify its header shows the full title and description,
+      full hash, author, committer, date, known branch/ref, and signature status
+      above the Changed Files paths and statuses. Unsigned commits say
+      **Unsigned**. Check that long values wrap and remain readable at the
+      largest Dynamic Type accessibility size.
 - [ ] Open a changed file and verify the diff title, old/new line numbers,
       monospaced text, addition/removal/hunk colors, vertical scrolling, and
       source-style horizontal scrolling for long lines without word wrapping,