🐛 Keep missing-shape diagnostics readable with mixed labels

Sort labels by their printed value so keyword and fallback string labels
can appear in the same diagnostic. The failing regression now passes.

Validation: schema and runner suites, 44 tests / 119 assertions.

AI-assisted-by: GPT-6

common/src/app/common/test_helpers/composable/core.cljc

@@ -251,7 +251,7 @@
     (when (nil? shape)
       (let [present (->> (vals (:objects page))
                          (map (comp thi/label :id))
-                         (sort)
+                         (sort-by str)
                          (vec))]
         (throw (ex-info (str "Unbound shape name: " (pr-str name)
                              ". Shapes present in current page: " (pr-str present))

common/test/common_tests/logic/composable_runner_test.cljc

@@ -582,3 +582,10 @@
         result (n/applied-result duplicate (tm/file before) (tm/file after))
         new-head (tm/shape-by-id after (:new-head result))]
     (t/is (= ((n/main-head-of "a") before) (:parent-id new-head)))))
+
+(t/deftest missing-shape-diagnostics-accept-mixed-label-types
+  (let [situation (setup/simple-component-with-labeled-copy)
+        error (try (tm/resolve-shape situation :missing)
+                   (catch #?(:clj Exception :cljs js/Error) error error))]
+    (t/is (= ::tm/unbound-shape-name (:type (ex-data error))))
+    (t/is (some #{:copy-child} (:present (ex-data error))))))