ui: per-host Jobs sub-tab; drop unused Settings stub

Adds /hosts/{id}/jobs page listing recent jobs for the host (newest
first, capped at 100) with click-through to /jobs/{id}. Converts the
Jobs placeholder <div> to a real <a> nav link; removes the Settings
stub entirely. Also registers durationHuman template func and a
.jobs-row CSS grid to match the existing .schd-row idiom.

internal/store/jobs_list_test.go

@@ -0,0 +1,83 @@
+package store
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+func TestListJobsByHost_OrderingAndLimit(t *testing.T) {
+	t.Parallel()
+	s := openTestStore(t)
+	ctx := context.Background()
+
+	const hostID = "h-jobs-1"
+	seedHost(t, s, hostID)
+
+	// Create three jobs with explicit CreatedAt offsets.
+	base := time.Now().UTC().Truncate(time.Second)
+	for i, d := range []time.Duration{-3 * time.Hour, -1 * time.Hour, -2 * time.Hour} {
+		j := Job{
+			ID:        "j-" + string(rune('a'+i)) + "0000000000000000000000000",
+			HostID:    hostID,
+			Kind:      "backup",
+			ActorKind: "user",
+			CreatedAt: base.Add(d),
+		}
+		// Truncate ID to 26 chars (ULID width); the test only needs it
+		// to be unique and stable across rows.
+		j.ID = j.ID[:26]
+		if err := s.CreateJob(ctx, j); err != nil {
+			t.Fatalf("create job %d: %v", i, err)
+		}
+	}
+
+	jobs, err := s.ListJobsByHost(ctx, hostID, 100)
+	if err != nil {
+		t.Fatalf("list: %v", err)
+	}
+	if len(jobs) != 3 {
+		t.Fatalf("want 3 jobs, got %d", len(jobs))
+	}
+	// Newest first ordering by created_at DESC.
+	for i := 0; i < len(jobs)-1; i++ {
+		if !jobs[i].CreatedAt.After(jobs[i+1].CreatedAt) && !jobs[i].CreatedAt.Equal(jobs[i+1].CreatedAt) {
+			t.Fatalf("ordering broken at %d: %v then %v", i, jobs[i].CreatedAt, jobs[i+1].CreatedAt)
+		}
+	}
+
+	// Limit clamps results.
+	limited, err := s.ListJobsByHost(ctx, hostID, 2)
+	if err != nil {
+		t.Fatalf("list limit: %v", err)
+	}
+	if len(limited) != 2 {
+		t.Fatalf("limit 2: want 2 jobs, got %d", len(limited))
+	}
+}
+
+func TestListJobsByHost_OnlyThisHost(t *testing.T) {
+	t.Parallel()
+	s := openTestStore(t)
+	ctx := context.Background()
+
+	const a, b = "h-jobs-a", "h-jobs-b"
+	seedHost(t, s, a)
+	seedHost(t, s, b)
+
+	now := time.Now().UTC()
+	if err := s.CreateJob(ctx, Job{ID: "01HZZZZZZZZZZZZZZZZZZZZZ01", HostID: a, Kind: "backup", ActorKind: "user", CreatedAt: now}); err != nil {
+		t.Fatalf("create a: %v", err)
+	}
+	if err := s.CreateJob(ctx, Job{ID: "01HZZZZZZZZZZZZZZZZZZZZZ02", HostID: b, Kind: "backup", ActorKind: "user", CreatedAt: now}); err != nil {
+		t.Fatalf("create b: %v", err)
+	}
+
+	jobs, err := s.ListJobsByHost(ctx, a, 100)
+	if err != nil {
+		t.Fatalf("list a: %v", err)
+	}
+	if len(jobs) != 1 || jobs[0].HostID != a {
+		t.Fatalf("expected 1 job for host a, got %d (%v)", len(jobs), jobs)
+	}
+}