Add risk assessment boundary model

Introduce RiskAssessmentBoundary as a first-class, self-nesting entity that
groups nodes within a risk assessment scope, and thread it through every
surface.

- coredata: new risk_assessment_boundaries table + migration, boundary_id on
  nodes, self-referential parent_boundary_id, entity type registration
- riskmanagement: boundary CRUD service methods, boundary_id wiring on node
  create/update, scope-membership and self-parent validation, nested-subgraph
  Mermaid rendering
- IAM: core:risk-assessment-boundary:{get,list,create,update,delete} actions
  and viewer/auditor read policies
- console GraphQL: RiskAssessmentBoundary type, connection, order enum, CRUD
  mutations, boundaries field on scope, boundaryId on nodes
- CLI: risk-assessment boundary command group and --boundary-id on nodes
- MCP: boundary tools and boundary_id on node tools
- n8n: boundary operations and boundary fields on node operations
- console UI: boundary list/create/edit, boundary selector on nodes, diagram
  refetch on boundary changes

Signed-off-by: Sacha Al Himdani <sacha@getprobo.com>

pkg/cmd/cmdutil/flags.go

@@ -74,3 +74,13 @@ func ValidateEnum(flag string, value string, allowed []string) error {
 		strings.Join(allowed, ", "),
 	)
 }
+
+// ValidateLimit checks that a --limit value is positive. A non-positive limit
+// would otherwise cause pagination to return no results without an error.
+func ValidateLimit(value int) error {
+	if value <= 0 {
+		return fmt.Errorf("invalid --limit value %d: must be greater than 0", value)
+	}
+
+	return nil
+}