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.Tests/RegistrationTests.cs

@@ -4,6 +4,9 @@ namespace Big.Tests;
 
 public class RegistrationTests
 {
+    // A fixed inscription moment for the approval tests; its exact value is irrelevant to them.
+    private static readonly DateTimeOffset Ingeschreven = new(2026, 1, 1, 0, 0, 0, TimeSpan.Zero);
+
     [Fact]
     public void Submitting_a_registration_starts_in_ingediend()
     {
@@ -103,7 +106,7 @@ public class RegistrationTests
         var registration = Registration.Submit("123456782");
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
 
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
         Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
     }
@@ -113,7 +116,7 @@ public class RegistrationTests
     {
         var registration = Registration.Submit("123456782");
 
-        var ex = Assert.Throws<InvalidOperationException>(() => registration.Approve());
+        var ex = Assert.Throws<InvalidOperationException>(() => registration.Approve(Ingeschreven));
 
         Assert.Contains("no zaak", ex.Message, StringComparison.OrdinalIgnoreCase);
         Assert.Equal(RegistrationStatus.Ingediend, registration.Status);
@@ -124,9 +127,9 @@ public class RegistrationTests
     {
         var registration = Registration.Submit("123456782");
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
-        var ex = Assert.Throws<InvalidOperationException>(() => registration.Approve());
+        var ex = Assert.Throws<InvalidOperationException>(() => registration.Approve(Ingeschreven));
         Assert.Contains("only an INGEDIEND", ex.Message);
         Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
     }
@@ -157,7 +160,7 @@ public class RegistrationTests
     {
         var registration = Registration.Submit("123456782");
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
         var ex = Assert.Throws<InvalidOperationException>(() => registration.TakeIntoBehandeling());
         Assert.Contains("only an INGEDIEND", ex.Message);
@@ -171,7 +174,7 @@ public class RegistrationTests
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
         registration.TakeIntoBehandeling();
 
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
         Assert.Equal(RegistrationStatus.Ingeschreven, registration.Status);
     }
@@ -218,7 +221,7 @@ public class RegistrationTests
         var approveEx = Assert.Throws<InvalidOperationException>(() =>
         {
             registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
-            registration.Approve();
+            registration.Approve(Ingeschreven);
         });
         Assert.Contains("IN_BEHANDELING", approveEx.Message);
 
@@ -277,7 +280,7 @@ public class RegistrationTests
     {
         var registration = Registration.Submit("123456782");
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
         var ex = Assert.Throws<InvalidOperationException>(() => registration.Withdraw());
         Assert.Contains("only an INGEDIEND", ex.Message);
@@ -336,7 +339,7 @@ public class RegistrationTests
     {
         var registration = Registration.Submit("123456782");
         registration.AttachZaak(new Uri("http://openzaak/zaken/api/v1/zaken/abc"));
-        registration.Approve();
+        registration.Approve(Ingeschreven);
 
         var ex = Assert.Throws<InvalidOperationException>(() => registration.Expire());
         Assert.Contains("only an INGEDIEND", ex.Message);