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/resolve.go

@@ -134,6 +134,10 @@ type Resolution struct {
 	// here without a store lookup.
 	Account     string
 	AccountHome string
+	// Capabilities are the machine's, as its profile reported them, carried from the node so a
+	// contribution placed only where the machine has something (`if-capability`, novox/hq ADR 0255)
+	// is decided here without a store lookup.
+	Capabilities map[string]bool
 
 	// Modules in the order they were resolved: assigned first, then what they pulled in.
 	Modules []Manifest
@@ -699,7 +703,7 @@ func Resolve(catalogue map[string]Manifest, assigned []string, node Node, world
 	}
 
 	resolution := Resolution{Node: node.Name, At: node.At, PublicDomain: node.PublicDomain,
-		Account: node.Account, AccountHome: node.AccountHome,
+		Account: node.Account, AccountHome: node.AccountHome, Capabilities: node.Capabilities,
 		Because: because, Needs: needs, Unhostable: unhostable, Kept: kept}
 	for _, n := range providersFirst(order, catalogue) {
 		resolution.Modules = append(resolution.Modules, catalogue[n])