Compose a module's Go service as a process the host runs (hq issue 213)

The controller is to be declared as a Go bundle run by a process instead of
an image (novox/hq issue 213, ADR 0188 §1, §3). The composer could not
express that honestly yet:

- a module declaring tools had every bundle served by the node's runtime,
  so the controller's own binary would have been launched a second time as
  an MCP child; a bundle one of the module's resources runs is now served
  only when it says `loads`
- a module's accounts went after the mesh-computed files, so secrets owned
  by the account a process runs as were refused on the first apply; a
  module's `user` resources now go first
- `prepares` derived its step only from a container; a process is now
  prepared by the same program with `prepare` as a run-once process
- a process may say what it `replaces` (a resource of its module it no
  longer declares), prefixed as the host records it, so the host keeps the
  old one running until the process is (needs mesh-host's `replaces`)

This lands before the controller's manifest uses any of it: the running
controller composes its own declaration, so the code that fills the new
shape must be live first.

internal/catalogue/manifest.go

@@ -1515,6 +1515,53 @@ func ParseManifest(raw []byte) (Manifest, error) {
 				"program that reads what the mesh delivered and reconciles",
 			m.Module, r["id"]))
 	}
+	// **What a process replaces is something the module no longer declares** (novox/hq issue 213).
+	// The host keeps it running until the process is, then removes it: so it is named by the id the
+	// module used to give it, it is never a resource the module still declares — that would be
+	// applied and removed by one declaration — and only a process that stays up has anything to
+	// hand over to. Said here, near the author, as the host would refuse it far away.
+	ids := map[string]bool{}
+	for _, r := range m.Resources {
+		ids[fmt.Sprint(r["id"])] = true
+	}
+	for _, r := range m.Resources {
+		raw, present := r["replaces"]
+		if !present {
+			continue
+		}
+		if fmt.Sprint(r["type"]) != "process" {
+			problems = append(problems, fmt.Sprintf(
+				"%s: %v says what it replaces, and only a process does", m.Module, r["id"]))
+			continue
+		}
+		if once, _ := r["run-once"].(bool); once || r["schedule"] != nil {
+			problems = append(problems, fmt.Sprintf(
+				"%s: %v replaces something and runs once or on a schedule — only a process that stays "+
+					"up is there a moment later to hand over to", m.Module, r["id"]))
+		}
+		list, ok := raw.([]any)
+		if !ok {
+			problems = append(problems, fmt.Sprintf(
+				"%s: %v replaces %v; replaces is a list of the ids this module no longer declares",
+				m.Module, r["id"], raw))
+			continue
+		}
+		for _, item := range list {
+			id, ok := item.(string)
+			switch {
+			case !ok || strings.TrimSpace(id) == "":
+				problems = append(problems, fmt.Sprintf(
+					"%s: %v replaces %v, which is not an id", m.Module, r["id"], item))
+			case strings.Contains(id, "."):
+				problems = append(problems, fmt.Sprintf(
+					"%s: %v replaces %q; a process replaces only a resource of its own module, named "+
+						"by its own id", m.Module, r["id"], id))
+			case ids[id]:
+				problems = append(problems, fmt.Sprintf(
+					"%s: %v replaces %q, which this module still declares", m.Module, r["id"], id))
+			}
+		}
+	}
 	// **A module that prepares its state must have code the mesh can run** (novox/hq ADR 0135). The
 	// preparation is the module's own program in its preparation mode, so it is derived from the
 	// resource that runs that program — and a module declaring none has asked for something the mesh
@@ -1522,7 +1569,7 @@ func ParseManifest(raw []byte) (Manifest, error) {
 	// quietly prepares nothing.
 	if m.Prepares && preparationTarget(m) == "" {
 		problems = append(problems, fmt.Sprintf(
-			"%s says it prepares its state, and declares no container running an artifact it built — "+
+			"%s says it prepares its state, and declares no container or process running an artifact it built — "+
 				"the preparation is this module's own program, so there has to be one for the mesh to "+
 				"run it in", m.Module))
 	}