feat: minimal frontend (run view, approvals, admin) with E2E smoke

- Tabs: Vorgaenge (run flows + history), Freigaben (decide tasks),
  Administration (Langflow link, import, deploy)
- Typed API client over vite /api proxy; tsc + vite build clean
- scripts/smoke_e2e.py: real LFX + API end-to-end, all green
- 34 backend tests green

frontend/src/components/ApprovalsTab.tsx

@@ -0,0 +1,95 @@
+import { useCallback, useEffect, useState } from "react";
+import { ApiError, api, type ApprovalTask } from "../api";
+
+export default function ApprovalsTab() {
+  const [tasks, setTasks] = useState<ApprovalTask[]>([]);
+  const [approver, setApprover] = useState("");
+  const [note, setNote] = useState("");
+  const [error, setError] = useState("");
+  const [busyId, setBusyId] = useState("");
+
+  const load = useCallback(async () => {
+    try {
+      setTasks(await api.listApprovals());
+    } catch (e) {
+      setError(e instanceof ApiError ? `${e.status}: ${e.message}` : String(e));
+    }
+  }, []);
+
+  useEffect(() => {
+    void load();
+  }, [load]);
+
+  async function decide(taskId: string, decision: "approve" | "reject") {
+    setBusyId(taskId);
+    setError("");
+    try {
+      const result = await api.decide(taskId, decision, approver, note);
+      setTasks((prev) =>
+        prev.map((t) => (t.id === taskId ? result.task : t)),
+      );
+    } catch (e) {
+      setError(e instanceof ApiError ? `${e.status}: ${e.message}` : String(e));
+    } finally {
+      setBusyId("");
+    }
+  }
+
+  const open = tasks.filter((t) => t.status === "open");
+  const done = tasks.filter((t) => t.status !== "open");
+
+  return (
+    <div>
+      <h2>Freigaben</h2>
+      {error && <p style={{ color: "crimson" }}>{error}</p>}
+      <div style={{ display: "flex", gap: 8, marginBottom: 12 }}>
+        <input
+          value={approver}
+          onChange={(e) => setApprover(e.target.value)}
+          placeholder="Name (Bearbeiter)"
+        />
+        <input
+          value={note}
+          onChange={(e) => setNote(e.target.value)}
+          placeholder="Notiz"
+          style={{ flex: 1 }}
+        />
+        <button onClick={() => void load()}>Aktualisieren</button>
+      </div>
+      <h3>Offen ({open.length})</h3>
+      {open.length === 0 && <p>Keine offenen Freigaben.</p>}
+      <ul>
+        {open.map((t) => (
+          <li key={t.id} style={{ marginBottom: 8 }}>
+            <strong>{t.title || t.id}</strong> · {t.tenant_id}
+            <br />
+            <code>{JSON.stringify(t.payload)}</code>
+            <br />
+            <button
+              onClick={() => void decide(t.id, "approve")}
+              disabled={busyId === t.id}
+            >
+              Freigeben
+            </button>{" "}
+            <button
+              onClick={() => void decide(t.id, "reject")}
+              disabled={busyId === t.id}
+            >
+              Ablehnen
+            </button>
+          </li>
+        ))}
+      </ul>
+      <h3>Entschieden ({done.length})</h3>
+      <ul>
+        {done.map((t) => (
+          <li key={t.id}>
+            <strong>{t.status}</strong> · {t.title || t.id} ·{" "}
+            {t.approver ?? "–"}
+            {t.decision_note ? ` · „${t.decision_note}“` : ""}
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}