Keep the recurring SCUM database poll bounded

Each dispatched poll is a durable job with two job log streams, so an
unbounded poll history would grow the platform store by roughly two
thousand jobs a day per server. A new poll now retires older terminal jobs
of the same template together with their job log streams, leaving at most
two rows per template while nothing is in flight.

platform/service/scum_query_ingest_test.go

@@ -1,6 +1,7 @@
 package service
 
 import (
+	"errors"
 	"testing"
 	"time"
 
@@ -225,3 +226,61 @@ func TestSCUMQueryProjectionIgnoresUndeclaredTemplateResults(t *testing.T) {
 		t.Fatalf("expected no projected users for an undeclared template, users=%+v err=%v", users, err)
 	}
 }
+
+func TestSCUMQueryJobRetentionKeepsBoundedHistory(t *testing.T) {
+	svc, _, instance, clock := newSCUMQueryIngestFixture(t)
+	aligned := time.Date(2026, 9, 16, 8, 0, 0, 0, time.UTC)
+	*clock = aligned
+	refreshSCUMQueryRunHeartbeat(t, svc, aligned)
+
+	playersJobs := func() []domain.Job {
+		jobs := countSCUMQueryJobs(t, svc, instance.ID)
+		players := make([]domain.Job, 0, len(jobs))
+		for _, job := range jobs {
+			if job.ExecutionInput.Inputs["templateKey"] == "scum.database.players" {
+				players = append(players, job)
+			}
+		}
+		return players
+	}
+
+	var firstJob domain.Job
+	for cycle := 0; cycle < 4; cycle++ {
+		if cycle > 0 {
+			*clock = aligned.Add(time.Duration(cycle) * 61 * time.Second)
+			refreshSCUMQueryRunHeartbeat(t, svc, *clock)
+		}
+		if err := svc.ReconcileSCUMQueryTemplates(instance.ID); err != nil {
+			t.Fatalf("reconcile cycle %d: %v", cycle, err)
+		}
+		for _, job := range playersJobs() {
+			if isTerminalJobState(job.State) {
+				continue
+			}
+			if cycle == 0 {
+				firstJob = job
+			}
+			job.State = domain.JobStateSucceeded
+			job.TerminalAt = *clock
+			if err := svc.store.Jobs().Update(job); err != nil {
+				t.Fatalf("complete query job: %v", err)
+			}
+		}
+	}
+
+	retained := playersJobs()
+	if len(retained) != scumQueryJobRetention {
+		t.Fatalf("expected %d retained player query jobs, got %d", scumQueryJobRetention, len(retained))
+	}
+	for _, job := range retained {
+		if !isTerminalJobState(job.State) {
+			t.Fatalf("retention must not remove in-flight jobs: %+v", job)
+		}
+	}
+	if _, err := svc.store.Jobs().Get(firstJob.ID); !errors.Is(err, repo.ErrNotFound) {
+		t.Fatalf("expected the oldest query job to be retired, err=%v", err)
+	}
+	if _, err := svc.store.LogStreams().Get(jobLogStreamID(firstJob.ID, "stdout")); !errors.Is(err, repo.ErrNotFound) {
+		t.Fatalf("expected retired query job log streams to be removed, err=%v", err)
+	}
+}