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/AdminTab.tsx

@@ -0,0 +1,118 @@
+import { useCallback, useEffect, useState } from "react";
+import {
+  ApiError,
+  LANGFLOW_URL,
+  api,
+  type FlowDefinition,
+  type FlowVersion,
+} from "../api";
+
+export default function AdminTab() {
+  const [flows, setFlows] = useState<FlowDefinition[]>([]);
+  const [versions, setVersions] = useState<Record<string, FlowVersion[]>>({});
+  const [langflowId, setLangflowId] = useState("");
+  const [importName, setImportName] = useState("");
+  const [error, setError] = useState("");
+  const [info, setInfo] = useState("");
+
+  const load = useCallback(async () => {
+    try {
+      const list = await api.listFlows();
+      setFlows(list);
+      const all: Record<string, FlowVersion[]> = {};
+      for (const f of list) {
+        all[f.id] = await api.listVersions(f.id);
+      }
+      setVersions(all);
+    } catch (e) {
+      setError(e instanceof ApiError ? `${e.status}: ${e.message}` : String(e));
+    }
+  }, []);
+
+  useEffect(() => {
+    void load();
+  }, [load]);
+
+  async function onImport() {
+    setError("");
+    setInfo("");
+    try {
+      const result = await api.importFlow(
+        langflowId,
+        importName.trim() ? importName.trim() : undefined,
+      );
+      setInfo(
+        `Importiert: ${result.definition.name} (Version ${result.version.version_no})`,
+      );
+      setLangflowId("");
+      setImportName("");
+      await load();
+    } catch (e) {
+      setError(e instanceof ApiError ? `${e.status}: ${e.message}` : String(e));
+    }
+  }
+
+  async function onDeploy(flowId: string, versionNo: number) {
+    setError("");
+    setInfo("");
+    try {
+      const version = await api.deployVersion(flowId, versionNo);
+      setInfo(`Deployed: Version ${version.version_no} (${version.lfx_flow_id})`);
+      await load();
+    } catch (e) {
+      setError(e instanceof ApiError ? `${e.status}: ${e.message}` : String(e));
+    }
+  }
+
+  return (
+    <div>
+      <h2>Administration</h2>
+      {error && <p style={{ color: "crimson" }}>{error}</p>}
+      {info && <p style={{ color: "green" }}>{info}</p>}
+      <p>
+        Flows werden visuell in Langflow entworfen:{" "}
+        <a href={LANGFLOW_URL} target="_blank" rel="noreferrer">
+          Langflow öffnen
+        </a>
+      </p>
+      <h3>Import aus Langflow</h3>
+      <div style={{ display: "flex", gap: 8, marginBottom: 12 }}>
+        <input
+          value={langflowId}
+          onChange={(e) => setLangflowId(e.target.value)}
+          placeholder="Langflow Flow-ID (UUID)"
+          style={{ flex: 1, fontFamily: "monospace" }}
+        />
+        <input
+          value={importName}
+          onChange={(e) => setImportName(e.target.value)}
+          placeholder="Name (optional)"
+        />
+        <button onClick={() => void onImport()} disabled={!langflowId.trim()}>
+          Importieren + Deployen
+        </button>
+      </div>
+      <h3>Flows + Versionen</h3>
+      {flows.length === 0 && <p>Keine Flows vorhanden.</p>}
+      <ul>
+        {flows.map((f) => (
+          <li key={f.id} style={{ marginBottom: 8 }}>
+            <strong>{f.name}</strong>
+            <ul>
+              {(versions[f.id] ?? []).map((v) => (
+                <li key={v.id}>
+                  v{v.version_no} ·{" "}
+                  {v.deployed_at ? `deployed (${v.lfx_flow_id})` : "nicht deployed"} ·{" "}
+                  {v.author || "–"}{" "}
+                  <button onClick={() => void onDeploy(f.id, v.version_no)}>
+                    Deployen
+                  </button>
+                </li>
+              ))}
+            </ul>
+          </li>
+        ))}
+      </ul>
+    </div>
+  );
+}