Rebuild admin pages around DataTable/AdminModal; restructure categories/groups and v2 groups API

Remove the generic $lib/svelte-admin CRUD layer and AdminTable.svelte; each
admin route now owns its own form/modal logic. Add DataTable.svelte,
superform-errors.ts, and profile-specific modal/field components.

Flatten proclamation categories/groups and drop subscription levels; add the
v2 groups API; update v1/v2 endpoints, serializers, auth, and regenerated
Prisma client with the new migrations.

Document the overhaul plan in docs/ADMIN_OVERHAUL.md.

src/lib/superform-errors.ts

@@ -0,0 +1,23 @@
+export function superFormErrorsToFieldErrors(superErrors: Record<string, unknown>): {
+	error: string;
+	fieldErrors: Record<string, string>;
+} {
+	const fieldErrors: Record<string, string> = {};
+	let formError = '';
+	for (const [key, value] of Object.entries(superErrors)) {
+		if (key === '_errors' && Array.isArray(value)) {
+			formError = (value[0] as string) ?? '';
+		} else if (
+			value &&
+			typeof value === 'object' &&
+			'_errors' in value &&
+			Array.isArray((value as Record<string, unknown>)._errors)
+		) {
+			const errMsg = ((value as Record<string, unknown>)._errors as string[])[0];
+			fieldErrors[key] = errMsg;
+		} else if (Array.isArray(value) && typeof value[0] === 'string') {
+			fieldErrors[key] = value[0];
+		}
+	}
+	return { error: formError, fieldErrors };
+}