feat(09-03): localize form schemas and resolve dropdown options

- Cached schemas stay source-key IR and each response carries its own meta.locale
- YAML option maps keep declaration order and scalar type; method options call DropdownOptions and fail boot without a provider

phrasebook/translator.go

@@ -116,6 +116,14 @@ func Activate[P interface{ ID() string }](app *backpack.App, plugins []P) error
 	return nil
 }
 
+// Locale returns the configured app locale. Request locales stay on the context.
+func (t *Translator) Locale() string {
+	if t == nil || strings.TrimSpace(t.locale) == "" {
+		return defaultLocale
+	}
+	return t.locale
+}
+
 // Get returns the translation for key using the request locale when present,
 // otherwise the configured app locale.
 func (t *Translator) Get(ctx context.Context, key string, params map[string]string) string {