feat(10-03): open, edit and save a record with toast and 422 feedback

- The SPA loads the backend::lang bundle before /auth/me, sets the
  document language from meta.locale and renders plural messages with
  Intl.PluralRules; interpolate mirrors phrasebook for :name/:Name/:NAME
- Create and record routes; mapWinterUrl maps recordUrl and redirects
  onto the controller's list, create and record routes only
- List rows open their record; FormView loads the form schema and the
  record, shows context-allowed fields in the span grid, saves values
  keyed by field name and toasts the resolved saved message
- A 422 puts each message under its field (aria-invalid,
  aria-describedby), shows the plural banner, focuses the first invalid
  field in schema order and clears a field's error on change
- The D-05 registry maps text, textarea, number and dropdown; any other
  type renders the unsupported-field box with the type in DM Mono
- The admin OpenAPI document declares the write request bodies
  (AdminRecord, AdminIDsRequest) and the list filter query as a
  deepObject, so the typed client can send them
- New backend::lang form.load_failed key; boardwalk/dist rebuilt

phrasebook/backend/lang/en/lang.yaml

@@ -68,6 +68,7 @@ form:
   error_fields:
     one: "Fix :count field marked below."
     other: "Fix :count fields marked below."
+  load_failed: The form could not be loaded.
   error_generic: The changes could not be saved. Please try again.
   unsaved_confirm: You have unsaved changes. Discard them?
   tab_errors:

phrasebook/backend/lang/pl/lang.yaml

@@ -74,6 +74,7 @@ form:
     few: "Popraw :count pola oznaczone poniżej."
     many: "Popraw :count pól oznaczonych poniżej."
     other: "Popraw :count pola oznaczonego poniżej."
+  load_failed: Nie udało się wczytać formularza.
   error_generic: Nie udało się zapisać zmian. Spróbuj ponownie.
   unsaved_confirm: Masz niezapisane zmiany. Porzucić je?
   tab_errors: