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

internal/tools/swagger2openapi/main.go

@@ -230,6 +230,17 @@ func convertParameter(p map[string]any) map[string]any {
 		}
 		out[k] = v
 	}
+	// Swagger 2.0 has no object query parameters; swag emits `type: object`
+	// for one. cabana reads such a parameter as bracketed keys
+	// (filter[<name>]=<value>), which is OpenAPI 3's deepObject style with
+	// string values.
+	if in, _ := out["in"].(string); in == "query" && schema["type"] == "object" {
+		if _, ok := schema["additionalProperties"]; !ok {
+			schema["additionalProperties"] = map[string]any{"type": "string"}
+		}
+		out["style"] = "deepObject"
+		out["explode"] = true
+	}
 	if len(schema) > 0 {
 		out["schema"] = schema
 	}