refactor(web): LabelEditor ignores blank labels; revert gratuitous tsconfig ES2022 bump

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/components/label-editor.test.tsx

@@ -26,7 +26,7 @@ test("typing EN and SV emits both labels; empty langs are omitted", async () =>
   renderApp(<Harness onChange={(v) => seen.push(v)} />);
   await userEvent.type(screen.getByLabelText(/label \(en\)/i), "Bronze");
   await userEvent.type(screen.getByLabelText(/label \(sv\)/i), "Brons");
-  const last = seen.at(-1)!;
+  const last = seen[seen.length - 1]!;
   expect(last).toEqual(
     expect.arrayContaining([
       { lang: "en", label: "Bronze" },

web/src/components/label-editor.tsx

@@ -21,7 +21,7 @@ export function LabelEditor({
   const set = (lang: string, label: string) => {
     const others = value.filter((l) => l.lang !== lang);
 
-    onChange(label ? [...others, { lang, label }] : others);
+    onChange(label.trim() ? [...others, { lang, label }] : others);
   };
 
   return (