test(theme): cover registerFontLicenses to restore the patch gate

codecov/patch failed at 66.66% because registerFontLicenses() was never
executed by a test — the licence-loading stream was covered but the
one-line glue that hands it to the LicenseRegistry was not.

Drain the registry itself after resetting Flutter's own collectors, so
the wiring is verified end to end rather than the function merely being
called. The drain runs inside tester.runAsync: testWidgets' fake-async
zone never advances the real asset read the collector awaits, which is
why an earlier attempt hung to the 10-minute test timeout instead of
failing.

Author: claude

test/app_theme_test.dart

@@ -192,11 +192,32 @@ void main() {
       );
     });
 
+    testWidgets('feeds the entries into the LicenseRegistry', (
+      WidgetTester tester,
+    ) async {
+      // Drop Flutter's own collectors so the registry yields only ours.
+      LicenseRegistry.reset();
+      addTearDown(LicenseRegistry.reset);
+
+      registerFontLicenses();
+
+      // runAsync escapes testWidgets' fake-async zone. The collector awaits a
+      // real asset read, which never completes on the fake clock — draining it
+      // directly hangs until the 10-minute test timeout.
+      final List<LicenseEntry>? entries = await tester.runAsync(
+        () => LicenseRegistry.licenses.toList(),
+      );
+
+      expect(
+        entries!.expand((LicenseEntry entry) => entry.packages),
+        containsAll(fontLicenseAssets.keys),
+      );
+    });
+
     testWidgets('yields one licence entry per family, carrying its text', (
       WidgetTester tester,
     ) async {
-      // Drains the collector directly rather than LicenseRegistry.licenses,
-      // which never completes under flutter_test.
+      // Drains the collector directly, bypassing the global registry.
       final List<LicenseEntry>? entries = await tester.runAsync(
         () => loadFontLicenses().toList(),
       );