feat(web): readable, grouped object detail (labels, placeholders, actions toolbar) (#45)

Refactor object-detail.tsx to resolve term/authority ids to labels via
FlexibleFieldValue, group flexible fields by def.group in definition order
(ungrouped → trailing "Other"), always show core fields with "—" placeholders,
and move Edit (button-styled Link) + Delete into a right-aligned toolbar.

Move formatDate into lib/format-date.ts so the component module no longer
co-exports a non-component (clears the react-refresh/only-export-components
warning); both flexible-field-value.tsx and object-detail.tsx import it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

web/src/objects/flexible-field-value.tsx

@@ -3,6 +3,7 @@ import { useTranslation } from "react-i18next";
 import type { components } from "../api/schema";
 import { useTerms, useAuthorities } from "../api/queries";
 import { labelText } from "../lib/labels";
+import { formatDate } from "../lib/format-date";
 
 type FieldDefinitionView = components["schemas"]["FieldDefinitionView"];
 
@@ -91,12 +92,3 @@ function pickLocalized(value: unknown, lang: string): string {
   }
   return value == null ? "—" : String(value);
 }
-
-/** Formats a date-only ISO string (YYYY-MM-DD) for display in the active locale.
- *  Parses as local midnight so a date-only value isn't shifted a day by tz. */
-export function formatDate(value: unknown, lang: string): string {
-  if (typeof value !== "string") return value == null ? "—" : String(value);
-  const date = new Date(`${value}T00:00:00`);
-  if (Number.isNaN(date.getTime())) return value;
-  return new Intl.DateTimeFormat(lang, { dateStyle: "medium" }).format(date);
-}