feat(260723-lvg): add "Jetzt abrufen" manual poll button to tender radar

PollNowButton sits next to the settings gear in the tender-radar header,
mirrors the DKV spinner/disabled UX, and bumps a refreshKey on success to
refetch ResultsList without touching any filter. Failure surfaces an
i18n error (de/en parity). pollNow() client hits POST
/modules/tender-radar/poll-now.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

apps/web/src/lib/tender-radar-api.ts

@@ -150,6 +150,23 @@ export async function listTenders(
   return res.json();
 }
 
+/**
+ * Trigger an immediate manual poll of all DUE tender sources (Quick
+ * 260723-lvg — "Jetzt abrufen"). Mirrors the DKV `checkNow` client shape.
+ * This is honest "fällige Quellen jetzt abrufen": 'day'-granularity
+ * sources still honor their nextDayToFetch cursor server-side — this is
+ * NOT a forced re-download.
+ * POST /modules/tender-radar/poll-now
+ */
+export async function pollNow(): Promise<{ ok: boolean }> {
+  const res = await fetch(`${API_URL}/modules/tender-radar/poll-now`, {
+    method: 'POST',
+    credentials: 'include',
+  });
+  if (!res.ok) throw new Error('Failed to trigger tender poll');
+  return res.json();
+}
+
 /**
  * Fetch the active-tender distribution by sourcePortal (D-12, UI-05) —
  * feeds CoverageBanner so a thin/single-source result list is not