Return index_url from /installedApps for dashboard app titles (#3352)

The dashboard derives a hostname title for anonymous (app-…) apps whose
uuid/name/title are all identical, falling back to the host of index_url.
That worked for launch/recent apps but not for apps that come only from
/installedApps, because the endpoint didn't return index_url.

Add apps.index_url to the SELECT (alongside apps.icon, relying on the
functional dependency on the apps.id primary key) and assert it in the
extension test.

extensions/installedApps.test.ts

@@ -132,6 +132,9 @@ describe('installedApps extension — handleInstalledApps', () => {
         expect(list[0].uid).toBe(app!.uid);
         expect(list[0].name).toBe(app!.name);
         expect(list[0].title).toBe(app!.title);
+        // index_url is required so the dashboard can derive a hostname title
+        // for anonymous (app-…) apps.
+        expect(list[0].index_url).toBe(app!.index_url);
         expect(Object.prototype.hasOwnProperty.call(list[0], 'iconUrl')).toBe(
             true,
         );

extensions/installedApps.ts

@@ -49,6 +49,7 @@ export const handleInstalledApps = async (
             apps.title,
             apps.description,
             apps.icon,
+            apps.index_url,
             MIN(perm.dt) AS installed_at
         FROM apps
         LEFT JOIN user_to_app_permissions AS perm ON apps.id = perm.app_id