feat(video-render): scaffold + nas_client webhook adapter (SP-7)

Dockerfile (python:3.12-slim), requirements (openai + google-cloud-storage + httpx + redis).
.env.example: OPENAI/GOOGLE/PIAPI/SEEDANCE keys + VIDEO_MEDIA_ROOT.
nas_client.webhook_update_task: call-time os.getenv (테스트 격리), respx mock 5 tests.
Plan-B-Video Phase 2.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

services/video-render/tests/test_nas_client.py

@@ -0,0 +1,70 @@
+"""nas_client — webhook adapter for video-render."""
+import pytest
+import respx
+import httpx
+
+from nas_client import webhook_update_task
+
+
+@pytest.fixture(autouse=True)
+def _env(monkeypatch):
+    monkeypatch.setenv("NAS_BASE_URL", "http://nas-test:18801")
+    monkeypatch.setenv("INTERNAL_API_KEY", "test-key")
+
+
+@respx.mock
+def test_webhook_update_task_sends_x_internal_key():
+    route = respx.post("http://nas-test:18801/api/internal/video/update").mock(
+        return_value=httpx.Response(200, json={"ok": True})
+    )
+    webhook_update_task("task-1", "processing", 30, message="downloading")
+    assert route.called
+    req = route.calls[0].request
+    assert req.headers["X-Internal-Key"] == "test-key"
+    import json
+    body = json.loads(req.content)
+    assert body["task_id"] == "task-1"
+    assert body["status"] == "processing"
+    assert body["progress"] == 30
+
+
+@respx.mock
+def test_webhook_update_task_with_video_url():
+    route = respx.post("http://nas-test:18801/api/internal/video/update").mock(
+        return_value=httpx.Response(200, json={"ok": True})
+    )
+    webhook_update_task("task-2", "succeeded", 100, message="완료",
+                       video_url="/media/video/task-2.mp4")
+    import json
+    payload = json.loads(route.calls[0].request.content)
+    assert payload["video_url"] == "/media/video/task-2.mp4"
+    assert payload["status"] == "succeeded"
+
+
+@respx.mock
+def test_webhook_update_task_with_error():
+    route = respx.post("http://nas-test:18801/api/internal/video/update").mock(
+        return_value=httpx.Response(200, json={"ok": True})
+    )
+    webhook_update_task("task-3", "failed", 0, error="Sora API rate limit")
+    import json
+    payload = json.loads(route.calls[0].request.content)
+    assert payload["error"] == "Sora API rate limit"
+
+
+@respx.mock
+def test_webhook_swallows_network_error(caplog):
+    respx.post("http://nas-test:18801/api/internal/video/update").mock(
+        side_effect=httpx.ConnectError("no host")
+    )
+    webhook_update_task("task-5", "processing", 10)
+    assert "task-5" in caplog.text
+
+
+@respx.mock
+def test_webhook_swallows_non_200(caplog):
+    respx.post("http://nas-test:18801/api/internal/video/update").mock(
+        return_value=httpx.Response(500, text="server error")
+    )
+    webhook_update_task("task-6", "processing", 50)
+    assert "task-6" in caplog.text