feat(reports): render generate-report form from OpenAPI spec

Replace hand-written GenerateReportPanel inputs with a generic loop over
extractFields("ReportQuery") + FormFieldRenderer; submit via
useResource("reports").create with server-side validation only.

react-openapi additions (all additive):
- lift items.enum into FieldConfig.enumValues for array-of-enum props
- extract schema `default` into FieldConfig.defaultValue
- new MultiEnumField renderer dispatched for isArray && enumValues
- FKFieldConfig.value: bind option values to a target property instead
  of the primary key (account names); sanitize-payload skips resolveFk
  when set
- new useFkFieldOptions hook encapsulating FK option loading/prefetch
- export extractFields, useFkFieldOptions, MultiEnumField

Drop now-unused granularityOptions/groupDimOptions helpers.

react-openapi/index.ts

@@ -5,6 +5,10 @@ export { useAppContext } from "./src/context/AppContext";
 export { useResource } from "./src/context/useResource";
 export { ListCellRenderer, DetailFieldRenderer, applyDisplayFormat } from "./src/components/fields";
 export { FormFieldRenderer } from "./src/components/fields/FormFieldRenderer";
+export { MultiEnumField } from "./src/components/fields/renderers/MultiEnumField";
+export { extractFields } from "./src/transformers/field-config";
+export { useFkFieldOptions } from "./src/hooks/useFkFieldOptions";
+export type { FkOption } from "./src/hooks/useFkFieldOptions";
 export { CurrencyField, formatCurrency } from "./src/components/fields/renderers/CurrencyField";
 export { FkMultiSelectField } from "./src/components/fields/renderers/FkMultiSelectField";
 export { SseStreamView } from "./src/components/SseStreamView";