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.go

@@ -288,6 +288,87 @@ func (s *Store) HasJobOfKind(ctx context.Context, hostID, kind string) (bool, er
 	return n > 0, nil
 }
 
+// ListJobsByHost returns recent jobs for hostID, ordered by
+// created_at DESC, limited to at most `limit` rows. limit ≤ 0 is
+// treated as no limit.
+func (s *Store) ListJobsByHost(ctx context.Context, hostID string, limit int) ([]Job, error) {
+	q := `SELECT id, host_id, kind, status, scheduled_id, source_group_id,
+	             actor_kind, actor_id, started_at, finished_at, exit_code,
+	             stats, error, created_at
+	      FROM jobs
+	      WHERE host_id = ?
+	      ORDER BY created_at DESC`
+	args := []any{hostID}
+	if limit > 0 {
+		q += ` LIMIT ?`
+		args = append(args, limit)
+	}
+	rows, err := s.db.QueryContext(ctx, q, args...)
+	if err != nil {
+		return nil, fmt.Errorf("store: list jobs by host: %w", err)
+	}
+	defer func() { _ = rows.Close() }()
+
+	var out []Job
+	for rows.Next() {
+		var (
+			j          Job
+			schedID    sql.NullString
+			groupID    sql.NullString
+			actorID    sql.NullString
+			startedAt  sql.NullString
+			finishedAt sql.NullString
+			exitCode   sql.NullInt64
+			stats      sql.NullString
+			errMsg     sql.NullString
+			createdAt  string
+		)
+		if err := rows.Scan(&j.ID, &j.HostID, &j.Kind, &j.Status, &schedID, &groupID,
+			&j.ActorKind, &actorID, &startedAt, &finishedAt,
+			&exitCode, &stats, &errMsg, &createdAt); err != nil {
+			return nil, fmt.Errorf("store: scan job row: %w", err)
+		}
+		if schedID.Valid {
+			v := schedID.String
+			j.ScheduledID = &v
+		}
+		if groupID.Valid {
+			v := groupID.String
+			j.SourceGroupID = &v
+		}
+		if actorID.Valid {
+			v := actorID.String
+			j.ActorID = &v
+		}
+		if startedAt.Valid {
+			t, _ := time.Parse(time.RFC3339Nano, startedAt.String)
+			j.StartedAt = &t
+		}
+		if finishedAt.Valid {
+			t, _ := time.Parse(time.RFC3339Nano, finishedAt.String)
+			j.FinishedAt = &t
+		}
+		if exitCode.Valid {
+			i := int(exitCode.Int64)
+			j.ExitCode = &i
+		}
+		if stats.Valid && stats.String != "" {
+			j.Stats = json.RawMessage(stats.String)
+		}
+		if errMsg.Valid {
+			v := errMsg.String
+			j.Error = &v
+		}
+		t, _ := time.Parse(time.RFC3339Nano, createdAt)
+		j.CreatedAt = t
+		out = append(out, j)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, fmt.Errorf("store: iterate jobs by host: %w", err)
+	}
+	return out, nil
+}
+
 func nullableStr(s string) any {
 	if s == "" {
 		return nil