feat(domain): Quartz cron job fires the herregistratie sweep; expose deadline on read (refs #18)

HerregistratieReminderJob (Quartz IJob) fires HerregistratieReminderSweep on a
daily cron wired in Big.Api (overridable via Quartz__Cron), and logs how many
reminders went out. Quartz.NET is used for this time-triggered fleet sweep,
distinct from the queue-draining pumps (ADR-0022). GET /registrations/{id} now
returns herregistratieVoor + herregistratieReminderVerstuurd. The scheduling
shell is excluded from mutation, mirroring the pumps.

refs #18

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);
 
@@ -40,6 +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>();
@@ -50,6 +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");
@@ -169,7 +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();
@@ -182,6 +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;