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.Infrastructure/HerregistratieReminderJob.cs

@@ -0,0 +1,26 @@
+using Big.Application;
+using Microsoft.Extensions.Logging;
+using Quartz;
+
+namespace Big.Infrastructure;
+
+/// <summary>
+/// The Quartz job that fires the herregistratie reminder sweep on a cron schedule (S-17, ADR-0022).
+/// A deliberately thin shell — it resolves the pure <see cref="HerregistratieReminderSweep"/> (Quartz's
+/// MS-DI job factory gives each fire its own scope) and logs how many reminders went out; all the
+/// sweep logic is unit-tested in the application layer. Quartz drives this — rather than a
+/// BackgroundService poll loop like the pumps — because it is a time-triggered fleet sweep, not a
+/// queue to drain (the distinction recorded in ADR-0022). <see cref="DisallowConcurrentExecutionAttribute"/>
+/// stops a slow sweep overlapping the next fire against the shared store.
+/// </summary>
+[DisallowConcurrentExecution]
+public sealed class HerregistratieReminderJob(
+    HerregistratieReminderSweep sweep, ILogger<HerregistratieReminderJob> logger) : IJob
+{
+    public async Task Execute(IJobExecutionContext context)
+    {
+        var reminded = await sweep.SweepAsync(context.CancellationToken);
+        logger.LogInformation(
+            "Herregistratie-sweep voltooid: {Count} herinnering(en) verstuurd.", reminded.Count);
+    }
+}