feat(12.2-03): add hasMany relation contracts, relation forms and child create

- RelationContract gains Kind (empty is belongsToMany) and ForeignKey, with kind-aware boot checks
- manage.form, view.form and pivot.form compile against the related or pivot model; $/ paths resolve inside the plugin
- view toolbarButtons accept create|update|delete|link|unlink, each the capability of its routes
- POST .../relations/{name}/records creates a child through the manage form; the server sets the hasMany key
- relation schema carries kind, deferrable and the localized forms; 17 new relation message keys in en and pl

modules/cabana/phase10_coverage_test.go

@@ -100,13 +100,14 @@ func TestPhase10Coverage(t *testing.T) {
 			"POST /{vendor}/{plugin}/{controller}/{id}/files/{field}",
 			"POST /{vendor}/{plugin}/{controller}/{id}/files/{field}/reorder",
 			"POST /{vendor}/{plugin}/{controller}/{id}/relations/{name}/link",
+			"POST /{vendor}/{plugin}/{controller}/{id}/relations/{name}/records",
 			"POST /{vendor}/{plugin}/{controller}/{id}/relations/{name}/unlink",
 			"PUT /settings/{code}",
 			"PUT /{vendor}/{plugin}/{controller}/{id}",
 			"PUT /{vendor}/{plugin}/{controller}/{id}/files/{field}/{file}",
 		}
 		if strings.Join(unsafe, "\n") != strings.Join(want, "\n") {
-			t.Fatalf("unsafe routes changed; extend TestPhase10CSRF (it expects 15 besides login):\n%s", strings.Join(unsafe, "\n"))
+			t.Fatalf("unsafe routes changed; extend TestPhase10CSRF (it expects 16 besides login):\n%s", strings.Join(unsafe, "\n"))
 		}
 		// The routes added in Phase 10 are safe reads: GET /lang and the shared
 		// nested pattern serving field options, filter options and relation lists.