A setting reaches only what declares it, the mesh places its own files, registration refuses a name

Three of novox/hq's group-4 leftovers, one branch.

Issue 173: a module's settings reached every route it contributed, every database it asked for and
every served fact its consumers read — a mail server's site name arrived at the proxy as a route
fact. A setting now overrides a key a contribution or served fact declares and adds none; a file
still merges any key, and a key nothing takes is named as stray instead of dropped silently.

Issue 174: the mesh's own files for a module — its bus credential, its merged config, its bindings —
were placed by the definition under /var/lib/mesh/<module>, 232 host paths in 50 definitions. A
directory may now say `place: "mesh"` and resolves to <root>/mesh/<module>; a directory beneath a
placed one may state its path as `${dir:<id>}/<rest>` and moves with it. The proof test resolves
both catalogues and compares: 48 definitions, no path moved. The controller's own manifest is
converted here; the catalogue in mesh-catalog.

ADR 0155: the installation check moves to registration. `module add` and a build's result both
refuse a definition that names an installation, in the check's words, with the way out; the build
stays recorded.

internal/catalogue/placed_paths_test.go

@@ -16,7 +16,9 @@ import (
 //
 // Two checkouts: MESH_CATALOGUE_BEFORE, the catalogue as it was, and MESH_CATALOGUE, as it is now.
 // Every module in both is resolved with the controller's own rule (dirsFor, dirFill) and compared
-// whole — not only the directories, but every string a directory's id was written into.
+// whole — not only the directories, but every string a directory's id was written into. Both
+// sides are resolved, so a manifest converted in two steps (issue 119, then issue 174) is judged
+// against the paths it named, not the text it used to name them with.
 func TestPlacedDirectoriesKeepTheirPaths(t *testing.T) {
 	before, after := os.Getenv("MESH_CATALOGUE_BEFORE"), os.Getenv("MESH_CATALOGUE")
 	if before == "" || after == "" {
@@ -42,7 +44,11 @@ func TestPlacedDirectoriesKeepTheirPaths(t *testing.T) {
 			t.Errorf("%s: %v", module, err)
 			continue
 		}
-		dirs := dirsFor(m, Rendering{})
+		earlier, err := ParseManifest(old)
+		if err != nil {
+			t.Errorf("%s before: %v", module, err)
+			continue
+		}
 		var was, is any
 		if err := json.Unmarshal(old, &was); err != nil {
 			t.Fatal(err)
@@ -50,7 +56,10 @@ func TestPlacedDirectoriesKeepTheirPaths(t *testing.T) {
 		if err := json.Unmarshal(now, &is); err != nil {
 			t.Fatal(err)
 		}
-		resolved := resolvedTree(is, dirs, module, t)
+		// Both sides resolved: the manifest before may itself already place some directories
+		// (issue 119's conversion), and what must not move is the path a machine sees.
+		was = resolvedTree(was, dirsFor(earlier, Rendering{}), module, t)
+		resolved := resolvedTree(is, dirsFor(m, Rendering{}), module, t)
 		if !reflect.DeepEqual(was, resolved) {
 			wasJSON, _ := json.MarshalIndent(was, "", "  ")
 			isJSON, _ := json.MarshalIndent(resolved, "", "  ")