feat(18.1-01): task 3 flat reorder on the server

- config_reorder.yaml without parentColumn on a record with no parent_id
  column compiles as a flat (WinterCMS Sortable) reorder; maxDepth above 0
  on it fails boot, an explicit parentColumn still means a tree
- ListReorder.Flat and AdminReorderTree.Flat (flat, omitempty); flat nodes
  carry parent_id null, a save writes only the sort column, a parent is a
  422 on nodes (reorder.flat_parent); 409 and duplicate rules unchanged
- swag descriptions, OpenAPI and schema.d.ts regenerated
- acme.catalog badges reorder fixture, TestReorderFlatCompile and
  TestReorderFlatSmoke; docs Flat reorder section and cabana README

modules/cabana/export_test.go

@@ -1,12 +1,37 @@
 package cabana
 
 import (
+	"fmt"
 	"time"
 
 	"git.golem15.com/golem15/summercms/modules/pact"
+	"git.golem15.com/golem15/summercms/modules/party"
 	"gorm.io/gorm"
 )
 
+// CompiledListSchema compiles the admin controllers of plugins without a
+// database or config, as Activate does, and returns the list schema of the
+// controller id (with its reorder object).
+func CompiledListSchema(plugins []party.Plugin, id string) (*ListSchema, error) {
+	items, err := collectControllers(plugins)
+	if err != nil {
+		return nil, err
+	}
+	types, err := compileFieldTypes(plugins)
+	if err != nil {
+		return nil, err
+	}
+	reg, err := compileRegistryWithTypes(items, types)
+	if err != nil {
+		return nil, err
+	}
+	cc, ok := reg.Get(id)
+	if !ok || cc.List == nil {
+		return nil, fmt.Errorf("cabana: no list schema for %s", id)
+	}
+	return cc.List, nil
+}
+
 // AdminAPIRoutes exposes the admin API route inventory (method plus
 // prefix-relative path) to the external conformance test.
 func AdminAPIRoutes() []string {