feat(10-02): backend strings, controller messages and declarative toolbar

- phrasebook ships the backend::lang admin strings (pl, en) with CLDR
  plural maps, loads them as namespace backend, applies
  pact.HasLangOverrides trees (lang/<locale>/<namespace>/<group>.yaml)
  after every namespace, and fails activation when a backend key cannot
  convert to plural forms
- Translator.Forms, Bundle, Resolved and Has serve keys as CLDR form maps
- Public GET /lang returns every backend::lang key for the request
  locale over the fallback locale, Cache-Control no-cache
- config_list, config_form and config_relation accept a strict messages
  block; omitted keys take framework defaults, schemas serve every message
  as CLDR forms, and activation fails on a missing phrase key
- toolbar.buttons is an ordered [create, delete] list; the Winter string
  form, duplicates, unknown actions and delete without showCheckboxes fail
  at boot, and create is dropped when the controller has no form
- Form schema serves the raw Winter redirects; scaffold emits the list
  syntax; form and relation schema routes are typed in the admin OpenAPI

cabana/list_schema.go

@@ -13,6 +13,7 @@ import (
 	"git.golem15.com/golem15/summercms/phrasebook"
 	"git.golem15.com/golem15/summercms/towel"
 	"github.com/goccy/go-yaml"
+	"github.com/goccy/go-yaml/ast"
 	"gorm.io/gorm"
 )
 
@@ -37,6 +38,7 @@ type listDocument struct {
 	DefaultSort      *listSortDocument `yaml:"defaultSort"`
 	Toolbar          *listToolbar      `yaml:"toolbar"`
 	Filter           string            `yaml:"filter"`
+	Messages         *listMessageKeys  `yaml:"messages"`
 }
 
 type listSortDocument struct {
@@ -45,7 +47,7 @@ type listSortDocument struct {
 }
 
 type listToolbar struct {
-	Buttons string `yaml:"buttons"`
+	Buttons toolbarButtons `yaml:"buttons"`
 	Search  *struct {
 		Prompt string `yaml:"prompt"`
 		Mode   string `yaml:"mode"`
@@ -123,7 +125,7 @@ func compileList(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSc
 			return nil, bootErr(pluginID, ctl.ID(), cfgPath, fmt.Errorf("unsupported search mode %s", mode))
 		}
 	}
-	buttons, err := compileToolbarButtons(doc.Toolbar)
+	buttons, err := compileToolbarButtons(doc.Toolbar, doc.ShowCheckboxes)
 	if err != nil {
 		return nil, bootErr(pluginID, ctl.ID(), cfgPath, err)
 	}
@@ -154,7 +156,7 @@ func compileList(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSc
 			return nil, err
 		}
 	}
-	return &ListSchema{
+	schema := &ListSchema{
 		Title:            doc.Title,
 		ModelClass:       doc.ModelClass,
 		RecordURL:        doc.RecordURL,
@@ -173,7 +175,13 @@ func compileList(pluginID string, ctl pact.AdminController, fsys fs.FS) (*ListSc
 		Filters:          filters,
 		RowActions:       rowActions,
 		BulkActions:      bulk,
-	}, nil
+	}
+	if doc.Messages != nil {
+		schema.messageKeys = *doc.Messages
+	}
+	keys := localizeMessages[listMessageKeys, ListMessages](context.Background(), nil, schema.listMessageKeySet())
+	schema.Messages = &keys
+	return schema, nil
 }
 
 func compileColumns(pluginID string, ctl pact.AdminController, fsys fs.FS, colPath string) ([]ListColumn, error) {
@@ -270,16 +278,58 @@ func compilePageOptions(recordsPerPage int, declared []int) ([]int, error) {
 	return options, nil
 }
 
-func compileToolbarButtons(toolbar *listToolbar) ([]string, error) {
-	if toolbar == nil || strings.TrimSpace(toolbar.Buttons) == "" {
+// toolbarButtons is the declarative toolbar.buttons list (D-14): built-in
+// actions in display order. A scalar (Winter's partial name) is rejected
+// with a pointer at the list syntax.
+type toolbarButtons struct {
+	items []string
+}
+
+// toolbarActions are the built-in toolbar actions; custom actions are Phase 10.1.
+var toolbarActions = map[string]struct{}{"create": {}, "delete": {}}
+
+func (b *toolbarButtons) UnmarshalYAML(node ast.Node) error {
+	node = unwrapNode(node)
+	switch n := node.(type) {
+	case nil, *ast.NullNode:
+		b.items = nil
+		return nil
+	case *ast.SequenceNode:
+		values := sequenceValues(n)
+		items := make([]string, 0, len(values))
+		seen := map[string]struct{}{}
+		for _, item := range values {
+			action, err := nodeString(unwrapNode(item))
+			if err != nil {
+				return fmt.Errorf("toolbar.buttons entries must be action names (create, delete)")
+			}
+			if _, ok := toolbarActions[action]; !ok {
+				return fmt.Errorf("toolbar.buttons: unsupported action %s (want create or delete)", action)
+			}
+			if _, dup := seen[action]; dup {
+				return fmt.Errorf("toolbar.buttons: duplicate action %s", action)
+			}
+			seen[action] = struct{}{}
+			items = append(items, action)
+		}
+		b.items = items
+		return nil
+	default:
+		return fmt.Errorf("toolbar.buttons must be a list of actions (create, delete); the Winter partial %q is not supported", nodeText(node))
+	}
+}
+
+func compileToolbarButtons(toolbar *listToolbar, showCheckboxes bool) ([]string, error) {
+	if toolbar == nil || len(toolbar.Buttons.items) == 0 {
 		return []string{}, nil
 	}
-	switch toolbar.Buttons {
-	case "list_toolbar":
-		return []string{"create"}, nil
-	default:
-		return nil, fmt.Errorf("unsupported action %s", toolbar.Buttons)
+	out := append([]string(nil), toolbar.Buttons.items...)
+	for _, action := range out {
+		if action == "delete" && !showCheckboxes {
+			return nil, fmt.Errorf("toolbar.buttons: delete needs showCheckboxes: true")
+		}
 	}
+	return out, nil
 }
 
 func compileDefaultSort(doc *listSortDocument, columns []ListColumn) (*ListSort, error) {
@@ -391,6 +441,8 @@ func (s *ListSchema) Localize(ctx context.Context, tr *phrasebook.Translator) (*
 	out.Filters = localizeListFilters(ctx, tr, s.Filters)
 	out.RowActions = localizeRowActions(ctx, tr, s.RowActions)
 	out.BulkActions = localizeBulkActions(ctx, tr, s.BulkActions)
+	messages := localizeMessages[listMessageKeys, ListMessages](ctx, tr, s.listMessageKeySet())
+	out.Messages = &messages
 	out.Meta = &FormMeta{Locale: locale}
 	return &out, nil
 }