Leave out a block its holder cannot render, and keep if-capability to known names on offered kinds (hq ADR 0255)

A piece whose shows the holder's template does not know rendered as nothing and failed
the whole machine's declaration; it is now left out and named, for push, plan and the
merge gate. quote escapes DEL, which TOML refuses bare. An if-capability nothing
detects, or on a kind a holder depends on, would drop a piece silently, so both are
refused.

internal/catalogue/declaration.go

@@ -291,6 +291,10 @@ type Composed struct {
 	// as `module/name`, sorted: what the next send will make. Never set on a declaration that is
 	// sent — a placeholder in a sealed file is a credential the process cannot read.
 	Foreseen []string
+	// Unplaced is every contribution the holder's template could not render into something, each
+	// naming its module and why (novox/hq ADR 0255): that piece is left out and the machine is told
+	// everything else. Push and plan say it; the merge gate refuses a change that adds one.
+	Unplaced []string
 }
 
 // ForeseenSealed is what stands for an own secret a send will make, in a composition asked ahead of
@@ -326,8 +330,8 @@ func (r Resolution) Compose(with Rendering) (Composed, error) {
 	owner := map[string]string{}
 	received := map[string]map[string][]Contribution{}
 	leftOut := map[string]string{}
-	var foreseen []string
-	resources, err := r.compose(with, owner, received, leftOut, &foreseen)
+	var foreseen, unplaced []string
+	resources, err := r.compose(with, owner, received, leftOut, &foreseen, &unplaced)
 	if err != nil {
 		return Composed{}, err
 	}
@@ -340,8 +344,9 @@ func (r Resolution) Compose(with Rendering) (Composed, error) {
 			"sealed": with.BusMembership, "mode": "0600",
 		})
 	}
+	sort.Strings(unplaced)
 	return Composed{Resources: resources, Owner: owner, Received: received, LeftOut: leftOut,
-		Foreseen: foreseen}, nil
+		Foreseen: foreseen, Unplaced: unplaced}, nil
 }
 
 // BusMembershipID names the resource carrying a machine's membership for the new bus, and
@@ -352,7 +357,7 @@ const BusMembershipPath = "/var/lib/mesh/membership-next.json"
 
 func (r Resolution) compose(with Rendering, owner map[string]string,
 	received map[string]map[string][]Contribution, leftOut map[string]string,
-	foreseen *[]string) ([]map[string]any, error) {
+	foreseen, unplaced *[]string) ([]map[string]any, error) {
 	// **A setting is judged where it is stored, and an impossible one costs a module, not a
 	// machine** (novox/hq ADR 0163, rule 6). A definition that moved under a stored setting makes
 	// this module uncomposable; it is left out of the declaration — its held things kept, its
@@ -970,7 +975,7 @@ func (r Resolution) compose(with Rendering, owner map[string]string,
 			// seat that places them (novox/hq ADR 0203, ADR 0204). Gathered from every module on
 			// the node, as the jails are, and **last of every placeholder pass**: shell code is a
 			// shell's own syntax, full of `${…}` no pass above should ever be shown.
-			if err := contributionsInto(copied, m, r.Modules, thisMachine, with, r.Capabilities); err != nil {
+			if err := contributionsInto(copied, m, r.Modules, thisMachine, with, r.Capabilities, unplaced); err != nil {
 				return nil, err
 			}
 			copied["id"] = m.Module + "." + fmt.Sprint(resource["id"])