feat(domain): herregistratie reminder sweep on a Quartz cron (S-17, closes #18) (#121)

## What & why

S-17: a BIG inscription is valid for a fixed term; before it lapses the zorgprofessional must herregistreren. This adds a **daily herregistratie reminder sweep**.

- **Domain:** `Approve(ingeschrevenOp)` now stamps the inscription moment; `HerregistratieVoor` derives the deadline (inscription + 5-year validity); `HerregistratieReminderDue(asOf)` is the single rule (inside the 90-day window, inscribed, not yet reminded); `MarkHerregistratieReminderVerstuurd()` is idempotent.
- **Store:** `FindDueForHerregistratieReminderAsync(asOf)` — the sweep's candidate set, filtered on the aggregate's own rule (no duplicated policy).
- **Application:** `HerregistratieReminderSweep` — pure over the store + an injected `TimeProvider`; flags + persists each due inscription, returns the reminded ids.
- **Infra/API:** `HerregistratieReminderJob` (Quartz `IJob`) fires the sweep on a daily cron (03:00, overridable via `Quartz__Cron`) and logs the count. `GET /registrations/{id}` surfaces `herregistratieVoor` + `herregistratieReminderVerstuurd`.

**Decisions (both raised with you before coding):** use Quartz.NET as the PRD names it — a genuine cron concern, distinct from the queue-draining pumps, which stay as-is (**ADR-0022**, proposal #120); and the reminder's observable effect is a flag on the aggregate + a log line (no outbound notification infra in v1). No coupling rule (§8) is touched — Quartz is internal to the Domain Service.

Closes #18
Closes #120

## Definition of Done

- [x] Linked Gitea issue (above).
- [x] Failing test committed before the implementation (red→green per layer: domain rule, store query, sweep).
- [x] Implementation makes the test pass; refactor commit for the 90-day knob.
- [x] Conventional Commits referencing the issue (`refs #18`).
- [ ] CI green — awaiting Gitea Actions.
- [ ] `docker compose up` reaches green health checks within 3 minutes — API boots locally with Quartz initialised; verified in CI compose smoke.
- [x] Docs updated — ADR-0022, demo-script, BACKLOG.
- [x] ADR added — `docs/architecture/adr-0022-quartz-scheduler.md`.
- [x] Demo note in `docs/demo-script.md`.

## Notes for reviewers

- **Ripple:** `Approve()` gained the inscription moment, so the two approving handlers (`ApproveRegistration`, `BeoordeelRegistratie`) now take an injected `TimeProvider`; existing tests pass a fixed clock. All three `IRegistrationStore` implementers (prod, unit fake, acceptance) got the new query.
- **Calibration knobs:** validity (5y) and reminder lead time (90d) are domain constants marked with `ponytail:` comments; promotion path to beheer config (S-15) noted in the ADR.
- **Mutation:** the Quartz job shell is excluded from Stryker, mirroring the pumps; all rule/sweep/query logic is covered.
- Local: 152 domain unit tests green; API boots with the Quartz scheduler and `/health` green.

Reviewed-on: #121

services/domain/Big.Api/Program.cs

@@ -1,6 +1,7 @@
 using Big.Application;
 using Big.Domain;
 using Big.Infrastructure;
+using Quartz;
 
 var builder = WebApplication.CreateBuilder(args);
 
@@ -15,6 +16,10 @@ builder.Services.AddSingleton(sp => sp.GetRequiredService<IConfiguration>()
 // The in-memory registration store is shared between the submit endpoint and the worker (ADR-0009).
 builder.Services.AddSingleton<IRegistrationStore, InMemoryRegistrationStore>();
 
+// The system clock, injected wherever a use case needs "now" (e.g. stamping the inscription moment
+// on approval, S-17). Injected as TimeProvider so tests can substitute a fixed clock.
+builder.Services.AddSingleton(TimeProvider.System);
+
 // The Workflow Client is one type behind two ports (start side + worker side); both resolve to the
 // same HttpClient-backed implementation — the only code that talks to Flowable (§8.2).
 builder.Services.AddHttpClient<FlowableWorkflowClient>();
@@ -36,6 +41,7 @@ builder.Services.AddScoped<OpenZaakJobProcessor>();
 builder.Services.AddScoped<BeoordelingEscalatieProcessor>();
 builder.Services.AddScoped<ExpireRegistrationWorker>();
 builder.Services.AddScoped<RegistratieVerlopenProcessor>();
+builder.Services.AddScoped<HerregistratieReminderSweep>();
 
 // The hosted external-task job worker polls Flowable and drives OpenZaakAanmaken to completion.
 builder.Services.AddHostedService<OpenZaakJobPump>();
@@ -46,6 +52,19 @@ builder.Services.AddHostedService<BeoordelingEscalatiePump>();
 // parks and expires each lapsed registration to VERLOPEN (S-10a, ADR-0017).
 builder.Services.AddHostedService<RegistratieVerlopenPump>();
 
+// The herregistratie reminder sweep runs on a daily cron via Quartz.NET (S-17, ADR-0022) — a
+// time-triggered fleet sweep, deliberately a different mechanism from the queue-draining pumps above.
+// The cron is overridable with Quartz__Cron; it defaults to 03:00 daily.
+builder.Services.AddQuartz(q =>
+{
+    var jobKey = new JobKey("herregistratie-reminder");
+    q.AddJob<HerregistratieReminderJob>(jobKey);
+    q.AddTrigger(t => t
+        .ForJob(jobKey)
+        .WithCronSchedule(builder.Configuration["Quartz:Cron"] ?? "0 0 3 * * ?"));
+});
+builder.Services.AddQuartzHostedService(o => o.WaitForJobsToComplete = true);
+
 var app = builder.Build();
 
 app.MapGet("/health", () => "Healthy");
@@ -165,7 +184,8 @@ app.MapGet("/registrations/{id}", async (string id, IRegistrationStore store, Ca
     return registration is null
         ? Results.NotFound()
         : Results.Ok(new RegistrationResponse(
-            registration.Id.ToString(), registration.Status.ToString(), registration.ZaakUrl?.ToString()));
+            registration.Id.ToString(), registration.Status.ToString(), registration.ZaakUrl?.ToString(),
+            registration.HerregistratieVoor?.ToString("O"), registration.HerregistratieReminderVerstuurd));
 });
 
 await app.RunAsync();
@@ -178,6 +198,11 @@ public sealed record WithdrawRequest(string Bsn);
 
 public sealed record ProvideDocumentsRequest(string Bsn, string ContentBase64, string? FileName = null, string? ContentType = null);
 
-public sealed record RegistrationResponse(string RegistrationId, string Status, string? ZaakUrl);
+public sealed record RegistrationResponse(
+    string RegistrationId,
+    string Status,
+    string? ZaakUrl,
+    string? HerregistratieVoor = null,
+    bool HerregistratieReminderVerstuurd = false);
 
 public partial class Program;