Let a seat receive blocks as data its holder renders, placed where the machine has the hardware (hq ADR 0255)

A module adding a battery to the bar had to write i3status-rust's TOML, so a second
bar could not take its place. node-bar now receives a bar-neutral block: the
contributor says what it shows, the holder renders it with its own template, places
every bar and place once, and a contribution may name a capability the machine must
report. The block is offered: the power module runs on servers without a bar.

internal/catalogue/backup_test.go

@@ -32,7 +32,7 @@ func TestHandWrittenBackupLinesOfAnOlderModuleArePlaced(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	placed, err := seatContributions([]Manifest{pg, mail}, BackupSeat, "backup", Rendering{}, nil)
+	placed, err := seatContributions([]Manifest{pg, mail}, Manifest{}, BackupSeat+":"+"backup", Rendering{}, nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}