feat(workflow): beoordeling escalation to teamlead after 14 days (S-14, closes #15) (#99)

## What & why

S-14: a beoordeling a behandelaar does not pick up within **14 days** escalates to the **teamlead**.

A non-interrupting `P14D` boundary timer on the `Beoordelen` user task fires an external-worker task
(`BeoordelingEscaleren`); the domain's escalation worker reassigns the still-open task's candidate group
from `behandelaar` to `teamlead`. The task keeps its identity — only who may claim it changes. The
escalation-via-external-worker decision is recorded in **ADR-0015** (proposal #98); it upholds §8.2
(the Workflow Client stays the only code that talks to Flowable) and keeps Flowable a stock image.

Closes #15

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation.
- [x] Implementation makes the test pass; refactor commit if structure improved.
- [x] Conventional Commits referencing the issue (`refs #NN`).
- [x] CI green — all Gitea Actions jobs.
- [x] `docker compose up` from a fresh clone reaches green health checks within 3 minutes (no new services; escalation is additive to the domain worker).
- [x] Docs updated (ADR-0015, demo note).
- [x] ADR added (`docs/architecture/adr-0015-beoordeling-escalation.md`).
- [x] Demo note in `docs/demo-script.md`.

## How it was built (TDD)

- **Workflow Client** (`IBeoordelingEscalatieClient`): acquire `BeoordelingEscaleren` jobs → find the open `Beoordelen` task in the instance → add `teamlead`/remove `behandelaar` candidate group → complete the job. Red → green.
- **Escalation drain loop** (`BeoordelingEscalatieProcessor`) + hosted `BeoordelingEscalatiePump`, mirroring the OpenZaak worker. Red → green.
- **BPMN**: non-interrupting `P14D` boundary timer on `Beoordelen` → external task → escalation end.
- **Both branches** (escalate after timeout; no-op when completed in time) covered by the `Een beoordeling escaleren` acceptance scenarios + Workflow Client unit tests.
- **Live integration**: `verify-domain` fires the timer early via Flowable's management API and asserts the reassignment to teamlead.

## Notes for reviewers

- Interface segregation: escalation is on `IBeoordelingEscalatieClient`, separate from the OpenZaak worker's `IExternalWorkerClient`.
- Reassignment is two REST hops (add teamlead, remove behandelaar); idempotent on redelivery — see ADR-0015 consequences.
- Local checks green: domain unit tests (104), acceptance (13), `dotnet format --verify-no-changes`, Release build (0 errors), **domain mutation 96.69%** (break 90). The `run-domain-check.sh` escalation path is CI-verified on verify-stack (local full-stack run is constrained here).
- `BeoordelingEscalatiePump` excluded from mutation, mirroring the existing `OpenZaakJobPump` exclusion.

Reviewed-on: #99

services/domain/Big.Tests/FlowableWorkflowClientTests.cs

@@ -306,4 +306,108 @@ public class FlowableWorkflowClientTests
         await Assert.ThrowsAsync<HttpRequestException>(
             () => client.CompleteBeoordelingAsync("task-1", BeoordelingsBesluit.Goedkeuren));
     }
+
+    // ── S-14 (#15): 14-day beoordeling escalation → reassign to teamlead (ADR-0015) ───────────────
+    // The BPMN parks a parallel escalation token on a non-interrupting P14D boundary timer, surfaced as
+    // an external-worker job on the BeoordelingEscaleren topic. The worker reassigns the still-open
+    // Beoordelen task from the behandelaar group to teamlead, then completes the escalation job.
+
+    [Fact]
+    public async Task Acquire_escalation_jobs_posts_the_escalation_topic_and_parses_the_process_instance()
+    {
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.OK,
+            """[{"id":"job-9","processInstanceId":"pi-1"}]"""));
+
+        var jobs = await client.AcquireBeoordelingEscalatieJobsAsync(3);
+
+        var job = Assert.Single(jobs);
+        Assert.Equal("job-9", job.JobId);
+        Assert.Equal("pi-1", job.ProcessInstanceId);
+        Assert.Equal("http://flowable/flowable-rest/external-job-api/acquire/jobs",
+            capture.Seen!.RequestUri!.ToString());
+        Assert.Contains("\"topic\":\"BeoordelingEscaleren\"", capture.Body);
+        Assert.Contains("\"numberOfTasks\":3", capture.Body);
+        Assert.Contains("\"workerId\":\"worker-x\"", capture.Body);
+    }
+
+    [Theory]
+    [InlineData("[]")]
+    [InlineData("null")]
+    public async Task Acquire_escalation_jobs_returns_empty_when_none_are_parked(string body)
+    {
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.OK, body));
+
+        Assert.Empty(await client.AcquireBeoordelingEscalatieJobsAsync(1));
+        Assert.NotNull(capture.Seen);
+    }
+
+    [Fact]
+    public async Task Reassign_moves_the_open_beoordelen_task_from_behandelaar_to_teamlead()
+    {
+        var requests = new List<(HttpMethod Method, string Url, string? Body)>();
+        var client = Client(new StubHandler(async req =>
+        {
+            requests.Add((req.Method, req.RequestUri!.ToString(),
+                req.Content is null ? null : await req.Content.ReadAsStringAsync()));
+            // The task query returns the still-open Beoordelen task parked in this instance.
+            return req.RequestUri!.AbsoluteUri.EndsWith("service/query/tasks")
+                ? new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent("""{"data":[{"id":"task-7"}],"total":1}""",
+                        Encoding.UTF8, "application/json"),
+                }
+                : new HttpResponseMessage(HttpStatusCode.OK);
+        }));
+
+        await client.ReassignBeoordelingToTeamleadAsync("pi-1");
+
+        // 1. Find the still-open Beoordelen task in this process instance.
+        var query = requests.Single(r => r.Url.EndsWith("service/query/tasks"));
+        Assert.Equal(HttpMethod.Post, query.Method);
+        Assert.Contains("\"processInstanceId\":\"pi-1\"", query.Body);
+        Assert.Contains("\"taskDefinitionKey\":\"Beoordelen\"", query.Body);
+        // 2. Add teamlead as a candidate group on that task.
+        var add = requests.Single(r => r.Method == HttpMethod.Post
+            && r.Url.EndsWith("service/runtime/tasks/task-7/identitylinks"));
+        Assert.Contains("\"group\":\"teamlead\"", add.Body);
+        Assert.Contains("\"type\":\"candidate\"", add.Body);
+        // 3. Remove behandelaar as a candidate group — the task now belongs to teamlead.
+        Assert.Contains(requests, r => r.Method == HttpMethod.Delete
+            && r.Url.EndsWith("service/runtime/tasks/task-7/identitylinks/groups/behandelaar/candidate"));
+    }
+
+    [Fact]
+    public async Task Reassign_is_a_no_op_when_the_beoordelen_task_is_no_longer_open()
+    {
+        // The behandelaar completed it just before the timer fired: nothing to reassign, no throw.
+        var methods = new List<HttpMethod>();
+        var client = Client(new StubHandler(req =>
+        {
+            methods.Add(req.Method);
+            return Task.FromResult(new HttpResponseMessage(HttpStatusCode.OK)
+            {
+                Content = new StringContent("""{"data":[],"total":0}""", Encoding.UTF8, "application/json"),
+            });
+        }));
+
+        await client.ReassignBeoordelingToTeamleadAsync("pi-1");
+
+        Assert.DoesNotContain(HttpMethod.Delete, methods);
+    }
+
+    [Fact]
+    public async Task Complete_escalation_job_posts_to_the_job_complete_endpoint()
+    {
+        var capture = new RequestCapture();
+        var client = Client(capture.Responds(HttpStatusCode.NoContent));
+
+        await client.CompleteBeoordelingEscalatieJobAsync("job-9");
+
+        Assert.Equal(HttpMethod.Post, capture.Seen!.Method);
+        Assert.Equal("http://flowable/flowable-rest/external-job-api/acquire/jobs/job-9/complete",
+            capture.Seen.RequestUri!.ToString());
+        Assert.Contains("\"workerId\":\"worker-x\"", capture.Body);
+    }
 }