feat: replace in_namespace relation with ownership-based namespace membership

Remove the in_namespace edge relation. A node now belongs to a namespace if that
namespace has has_ownership on it. This simplifies the model: namespace membership
is determined by the ownership chain rather than a separate relation type.

Changes:
- Remove RelInNamespace constant
- Add Namespace fields to AddInput, UpdateInput, and ListFilter
- Update Add() to resolve namespace from input and assign it as owner
- Update List() to filter by namespace ownership instead of in_namespace edges
- Update() can now transfer nodes between namespaces via ownership transfer
- Remove in_namespace self-references from ensureNamespace/ensureGlobalNamespace

The ownership chain now fully describes both permissions and namespace membership,
reducing redundancy. All tests pass with the new model.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/cmd/add.go

@@ -43,7 +43,7 @@ var addCmd = &cobra.Command{
 			input.Rels = append(input.Rels, service.RelInput{Type: models.RelType("_prio::" + cPrio), Target: ""})
 		}
 		if cNamespace != "" {
-			input.Rels = append(input.Rels, service.RelInput{Type: models.RelInNamespace, Target: cNamespace})
+			input.Namespace = cNamespace
 		}
 		if cAssignee != "" {
 			input.Rels = append(input.Rels, service.RelInput{Type: models.RelAssignee, Target: cAssignee})

src/cmd/list.go

@@ -46,7 +46,7 @@ var listCmd = &cobra.Command{
 			filter.Rels = append(filter.Rels, service.RelInput{Type: models.RelType("_type::" + lType), Target: ""})
 		}
 		if lNamespace != "" {
-			filter.Rels = append(filter.Rels, service.RelInput{Type: models.RelInNamespace, Target: lNamespace})
+			filter.Namespace = lNamespace
 		}
 		if lAssignee != "" {
 			filter.Rels = append(filter.Rels, service.RelInput{Type: models.RelAssignee, Target: lAssignee})

src/cmd/output.go

@@ -49,7 +49,7 @@ var (
 		"low":    {" ", "low", cDim},
 		"":       {" ", "n/a", cDim},
 	}
-	relIcons    = map[string]string{"blocks": "\uf068", "subtask": "\uf0da", "related": "\uf0c1", "assignee": "\uf007", "in_namespace": "\uf07b"}
+	relIcons = map[string]string{"blocks": "\uf068", "subtask": "\uf0da", "related": "\uf0c1", "assignee": "\uf007"}
 	prioRanks   = map[string]int{"high": 3, "medium": 2, "low": 1}
 	statusRanks = map[string]int{"open": 2, "": 1, "done": 0}
 )
@@ -94,24 +94,12 @@ func PrintNodes(w io.Writer, svc service.NodeService, nodes []*models.Node, json
 	})
 
 	for _, n := range nodes {
-		n_rels := n.Relations
-		ns_rel_node_ids := n_rels[string(models.RelInNamespace)]
-		ns_rel_node_titles := make([]string, 0, len(ns_rel_node_ids))
-		for _, id := range ns_rel_node_ids {
-			ns_rel_node, err := svc.GetByID(id)
-			if err != nil {
-				ns_rel_node_titles = append(ns_rel_node_titles, id)
-				continue
-			}
-			ns_rel_node_titles = append(ns_rel_node_titles, ns_rel_node.Title)
-		}
-		fmt.Fprintf(w, "  %s %s %s %s %s %s %s",
+		fmt.Fprintf(w, "  %s %s %s %s %s %s",
 			cDim.Sprint(n.ID),
 			render(prioRM, n.GetProperty("prio"), true),
 			render(statusRM, n.GetProperty("status"), true),
 			render(typeRM, n.GetProperty("type"), true),
 			cTitle.Sprint(truncate(n.Title, 80)),
-			cDim.Sprint("["+strings.Join(ns_rel_node_titles, ",")+"]"),
 			dueDateShort(n.DueDate),
 		)
 		tags := n.GetDisplayTags()

src/cmd/update.go

@@ -61,7 +61,7 @@ var updateCmd = &cobra.Command{
 			input.AddRels = append(input.AddRels, service.RelInput{Type: models.RelType("_prio::" + uPrio), Target: ""})
 		}
 		if cmd.Flags().Changed("namespace") {
-			input.AddRels = append(input.AddRels, service.RelInput{Type: models.RelInNamespace, Target: uNamespace})
+			input.Namespace = &uNamespace
 		}
 		if cmd.Flags().Changed("assignee") {
 			input.AddRels = append(input.AddRels, service.RelInput{Type: models.RelAssignee, Target: uAssignee})