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

backend/scripts/smoke_e2e.py

@@ -0,0 +1,127 @@
+"""Manual end-to-end smoke: real LFX + real API, frontend-shaped calls.
+
+Usage (from backend/):
+    TEST_DATABASE_URL=postgresql+psycopg://... uv run python scripts/smoke_e2e.py
+Exits non-zero on any unexpected status/body.
+"""
+
+from __future__ import annotations
+
+import json
+import os
+import subprocess
+import sys
+import time
+import urllib.request
+from pathlib import Path
+
+BACKEND = Path(__file__).resolve().parent.parent
+VENV_BIN = BACKEND / ".venv" / "bin"
+FIXTURES = BACKEND / "tests" / "fixtures" / "flows"
+
+LFX_PORT = 6004
+API_PORT = 8000
+LFX_KEY = "lfx-759GsfJKjAeOBZ_44-cll9WdHp_yfYn_tIg7eHG38Rs"
+
+
+def wait_healthy(url: str, timeout: int = 180) -> None:
+    deadline = time.time() + timeout
+    while time.time() < deadline:
+        try:
+            with urllib.request.urlopen(url, timeout=3) as r:
+                if r.status == 200:
+                    return
+        except OSError:
+            time.sleep(1)
+    raise RuntimeError(f"never healthy: {url}")
+
+
+def api(method: str, path: str, body: dict | None = None) -> tuple[int, dict | str]:
+    import httpx
+
+    with httpx.Client(base_url=f"http://127.0.0.1:{API_PORT}", timeout=120) as c:
+        r = c.request(method, path, json=body)
+        try:
+            return r.status_code, r.json()
+        except ValueError:
+            return r.status_code, r.text
+
+
+def check(name: str, cond: bool, detail: str = "") -> None:
+    print(f"[{'OK' if cond else 'FAIL'}] {name} {detail}")
+    if not cond:
+        raise SystemExit(f"smoke failed: {name} {detail}")
+
+
+def main() -> None:
+    flow_dir = Path("/tmp/smoke-e2e-flows")
+    flow_dir.mkdir(exist_ok=True)
+    (flow_dir / "seed.json").write_text(
+        (FIXTURES / "simple_rule.json").read_text()
+    )
+    env = {
+        **os.environ,
+        "LFX_API_KEY": LFX_KEY,
+        "DATABASE_URL": os.environ["TEST_DATABASE_URL"],
+        "LFX_URL": f"http://127.0.0.1:{LFX_PORT}",
+        "LFX_API_KEY": LFX_KEY,
+        "CALLBACK_BASE_URL": f"http://127.0.0.1:{API_PORT}",
+    }
+    lfx = subprocess.Popen(
+        [str(VENV_BIN / "lfx"), "serve", "--host", "127.0.0.1",
+         "--port", str(LFX_PORT), "--flow-dir", str(flow_dir), str(flow_dir)],
+        stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, env=env,
+    )
+    uvicorn = subprocess.Popen(
+        [str(VENV_BIN / "uvicorn"), "app.main:app", "--host", "127.0.0.1",
+         "--port", str(API_PORT)],
+        cwd=str(BACKEND), stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL,
+        env=env,
+    )
+    try:
+        wait_healthy(f"http://127.0.0.1:{LFX_PORT}/health")
+        wait_healthy(f"http://127.0.0.1:{API_PORT}/health")
+
+        s, flows = api("GET", "/api/flows")
+        check("list flows", s == 200 and isinstance(flows, list))
+
+        s, flow = api("POST", "/api/flows", {"name": "smoke-dach"})
+        check("create flow", s == 201, json.dumps(flow)[:120])
+        fid = flow["id"]
+
+        fx = json.loads((FIXTURES / "simple_rule.json").read_text())
+        s, ver = api(
+            "POST", f"/api/flows/{fid}/versions",
+            {"langflow_json": fx, "author": "smoke"},
+        )
+        check("create version", s == 201, f"v{ver.get('version_no')}")
+
+        s, dep = api("POST", f"/api/flows/{fid}/versions/1/deploy")
+        check("deploy", s == 200 and dep.get("lfx_flow_id"), json.dumps(dep)[:160])
+
+        s, run = api(
+            "POST", f"/api/flows/{fid}/run",
+            {"input": {"betrag": 120000, "schwelle": 200000}},
+        )
+        check("run standard", s == 200 and run.get("status") == "completed",
+              json.dumps(run.get("output"))[:120])
+
+        s, run2 = api(
+            "POST", f"/api/flows/{fid}/run",
+            {"input": {"betrag": 999000, "schwelle": 200000}},
+        )
+        check("run sonderfall", s == 200 and "Sonderfall" in (run2.get("output") or {}).get("result", ""))
+
+        s, tasks = api("GET", "/api/approvals")
+        check("approvals empty (no callback flow)", s == 200 and tasks == [])
+
+        print("smoke E2E: all green")
+    finally:
+        uvicorn.terminate()
+        lfx.terminate()
+
+
+if __name__ == "__main__":
+    if "TEST_DATABASE_URL" not in os.environ:
+        sys.exit("TEST_DATABASE_URL must be set")
+    main()