test(infra): verify-notifications smoke + CI job for the OZ→NRC path (refs #56)

make verify-notifications brings the stack up, seeds a published BIG zaaktype, and
asserts a zaak-create notification is delivered to a webhook-sink abonnement. The
sink + driver run as containers inside the compose network and reach OpenZaak/NRC by
container IP (the runner can't reach published ports, and a single-label host isn't
URL-valid). The sink enforces a bearer token because NRC refuses an unauthenticated
callback. New 'notifications' Gitea Actions job runs it (Docker-only).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

infra/verify-notification-driver.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+"""Drive the OpenZaak → NRC notification check from *inside* the compose network.
+
+Registers an abonnement on the `zaken` kanaal pointing at a webhook sink, then
+creates a zaak against the published BIG zaaktype. OpenZaak publishes a
+`zaken`/`create` notification; NRC delivers it to the sink. The host harness
+(infra/verify-notifications.sh) then asserts the sink received it.
+
+Reached by container IP, not service name: OpenZaak/NRC validate URLs with Django's
+URLValidator, which rejects a single-label host like `openzaak`. Stdlib only.
+Env: OZ_BASE, NRC_BASE, SINK_CALLBACK, SINK_AUTH, OZ_CLIENT_ID, OZ_SECRET.
+"""
+import base64
+import hashlib
+import hmac
+import json
+import os
+import sys
+import time
+import urllib.error
+import urllib.request
+
+OZ = os.environ["OZ_BASE"].rstrip("/")
+NRC = os.environ["NRC_BASE"].rstrip("/")
+SINK_CALLBACK = os.environ["SINK_CALLBACK"]
+SINK_AUTH = os.environ.get("SINK_AUTH", "Bearer notification-sink-token")
+CID = os.environ.get("OZ_CLIENT_ID", "big-reference-seed")
+SECRET = os.environ.get("OZ_SECRET", "insecure-dev-secret-change-me")
+RSIN = "517439943"
+
+
+def token():
+    b64 = lambda b: base64.urlsafe_b64encode(b).rstrip(b"=")
+    seg = (
+        b64(json.dumps({"alg": "HS256", "typ": "JWT"}, separators=(",", ":")).encode())
+        + b"."
+        + b64(json.dumps(
+            {"iss": CID, "iat": int(time.time()), "client_id": CID,
+             "user_id": "verify", "user_representation": "verify"},
+            separators=(",", ":")).encode())
+    )
+    return (seg + b"." + b64(hmac.new(SECRET.encode(), seg, hashlib.sha256).digest())).decode()
+
+
+def call(method, url, body=None, crs=False):
+    headers = {"Authorization": "Bearer " + token(),
+               "Content-Type": "application/json", "Accept": "application/json"}
+    if crs:
+        headers["Accept-Crs"] = "EPSG:4326"
+        headers["Content-Crs"] = "EPSG:4326"
+    data = json.dumps(body).encode() if body is not None else None
+    try:
+        with urllib.request.urlopen(
+            urllib.request.Request(url, data=data, method=method, headers=headers), timeout=30
+        ) as r:
+            return r.status, json.loads(r.read() or "null")
+    except urllib.error.HTTPError as e:
+        return e.code, json.loads(e.read() or "null")
+
+
+def main():
+    status, ab = call("POST", f"{NRC}/api/v1/abonnement", {
+        "callbackUrl": SINK_CALLBACK,
+        "auth": SINK_AUTH,
+        "kanalen": [{"naam": "zaken", "filters": {}}],
+    })
+    if status != 201:
+        sys.exit(f"create abonnement -> {status}: {json.dumps(ab)}")
+    print(f"abonnement: {ab['url']}")
+
+    status, body = call(
+        "GET", f"{OZ}/catalogi/api/v1/zaaktypen?identificatie=BIG-REGISTRATIE&status=definitief")
+    results = body.get("results", []) if status == 200 else []
+    if not results:
+        sys.exit("no published BIG-REGISTRATIE zaaktype — seed with OZ_PUBLISH=1 first")
+    zaaktype = results[0]["url"]
+
+    status, zaak = call("POST", f"{OZ}/zaken/api/v1/zaken", {
+        "bronorganisatie": RSIN, "verantwoordelijkeOrganisatie": RSIN,
+        "zaaktype": zaaktype, "startdatum": time.strftime("%Y-%m-%d"),
+        "vertrouwelijkheidaanduiding": "openbaar",
+    }, crs=True)
+    if status != 201:
+        sys.exit(f"create zaak -> {status}: {json.dumps(zaak)}")
+    # The harness greps the sink for this exact URL.
+    print(f"ZAAK_CREATED {zaak['url']}")
+
+
+if __name__ == "__main__":
+    main()