fix: flag A/B/C persistence, catalog sort+reorder, offer category pools

- Fix duplicate tier INSERT bug (useState not syncing after router.refresh)
- Add column sort by clicking headers in service catalog
- Add drag-and-drop column reordering (persisted in localStorage)
- Add Categorie Offerta section in Impostazioni (tipo/obiettivo/categoria pools)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/admin/offers/OfferEditorClient.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useState, useMemo, useTransition } from "react";
+import { useState, useMemo, useTransition, useEffect } from "react";
 import { useRouter } from "next/navigation";
 import Link from "next/link";
 import {
@@ -86,6 +86,13 @@ export function OfferEditorClient({
   const [tipoTags, setTipoTags] = useState<string[]>(data.tipoTags);
   const [obiettivoTags, setObiettivoTags] = useState<string[]>(data.obiettivoTags);
 
+  // After first draft save router.refresh() assigns real DB IDs to new tiers.
+  // Re-sync tiers state when those IDs arrive so subsequent saves UPDATE instead of INSERT.
+  const tierIdKey = data.tiers.map((t) => t.id).sort().join(",");
+  useEffect(() => {
+    setTiers(padTiers(data.tiers));
+  }, [tierIdKey]); // eslint-disable-line react-hooks/exhaustive-deps
+
   const [categoriaOptions, setCategoriaOptions] = useState<string[]>(fieldOptions.categoria);
   const [ticketOptions, setTicketOptions] = useState<string[]>(fieldOptions.ticket);
   const [tipoOptions, setTipoOptions] = useState<string[]>(fieldOptions.tipo);