Seats keep their former names, so a rename breaks nothing (ADR 0122, phase 2)

Phase 1 made the set data; a rename still broke every reference to the old
name. This adds the stable identity: a seat's canonical name changes and its
old name becomes an alias that resolves to it forever. SeatNamed and the holder
and display matching resolve a name (former or current) to its seat, so a
manifest's claim, a held record, the git-seat lookup and the build machine's
embedded set all go on working unchanged after a rename. seat_alias table
(migration 0035), inventory Aliases/RenameSeat, openInventory loads them, and a
'seat rename <from> <to>' command does the whole thing — one operation, no
rebuild, no re-registration, no freeze. Behaviour-neutral until a seat is
renamed. Validated against postgres.

cmd/mesh-controller/stores.go

@@ -102,6 +102,10 @@ func openInventory(ctx context.Context) (*inventory.Inventory, error) {
 	if seats, err := inv.Seats(ctx); err == nil {
 		catalogue.UseSeats(seats)
 	}
+	// And the former names, so a reference to a seat's old name resolves after a rename (ADR 0122).
+	if aliases, err := inv.Aliases(ctx); err == nil {
+		catalogue.UseAliases(aliases)
+	}
 	return inv, nil
 }