🐛 Give the branches shortcut the static label develop requires

develop's translation cleanup (penpot/penpot#11853) makes every shortcut
definition carry a :label fn holding a literal (tr "shortcuts.<id>"),
and command-definitions-carry-static-labels pins it. :open-branches,
added on the branching fork, had no label and no English string, so the
shortcuts panel showed the raw key and the test failed by name on the
rebase.

The label reads "Branches", the name the main menu already gives the
same panel.

frontend tests: 1200 tests, 4580 assertions, 0 failures.

AI-assisted-by: claude-opus-5-5

frontend/src/app/main/data/workspace/shortcuts.cljs

@@ -659,6 +659,7 @@
                                 (dw/toggle-layout-flag :document-history))}
 
    :open-branches        {:tooltip (ds/meta-alt "B")
+                          :label (fn [] (tr "shortcuts.open-branches"))
                           :command (ds/ca-mod "b")
                           :subsections [:panels]
                           :fn #(emit-when-no-readonly

frontend/translations/en.po

@@ -5146,6 +5146,10 @@ msgstr "Color picker"
 msgid "shortcuts.open-comments"
 msgstr "Go to viewer comment section"
 
+#: src/app/main/data/workspace/shortcuts.cljs:661
+msgid "shortcuts.open-branches"
+msgstr "Branches"
+
 #: src/app/main/data/workspace/shortcuts.cljs:763
 msgid "shortcuts.open-dashboard"
 msgstr "Go to dashboard"