feat(09-02): implement admin quote builder UI with server actions

- src/lib/quote-actions.ts: createQuote server action with nanoid tokens and atomic DB transaction
- src/components/admin/quotes/QuoteBuilderForm.tsx: Two-column form (left: client/offer/price inputs, right: live preview)
- src/components/admin/quotes/OfferSelector.tsx: Grouped dropdown for macro/micro offer selection
- src/components/admin/quotes/PriceOverrideInput.tsx: Price input with server validation feedback
- src/components/admin/quotes/QuotePreview.tsx: Live preview card showing offer details and calculated total
- src/app/admin/quotes/new/page.tsx: Quote builder page rendering form with data from DB
- src/app/admin/quotes/new/actions.ts: Re-export of createQuote for page-level action imports
- src/lib/admin-queries.ts: Added getAllOfferMacrosWithMicros() query for form population

Features:
- Admin selects client and offer (required fields)
- Form validates on blur and displays success/error states
- Server action validates data and rejects if total mismatch
- On success, displays public /quote/[token] link with copy button
- Quote saved as draft state with immutable accepted_total

Completes Phase 9 Plan 2 Wave 1: Admin UI Layer

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/app/admin/quotes/new/page.tsx

@@ -0,0 +1,28 @@
+import { Card } from "@/components/ui/card";
+import { QuoteBuilderForm } from "@/components/admin/quotes/QuoteBuilderForm";
+import { getAllClientsWithPayments } from "@/lib/admin-queries";
+import { getAllOfferMacrosWithMicros } from "@/lib/admin-queries";
+
+export const revalidate = 0;
+
+export default async function QuoteBuilderPage() {
+  const [clientsData, offersData] = await Promise.all([
+    getAllClientsWithPayments(),
+    getAllOfferMacrosWithMicros(),
+  ]);
+
+  return (
+    <div className="space-y-6">
+      <div>
+        <h1 className="text-3xl font-bold text-gray-900">Crea Preventivo</h1>
+        <p className="text-gray-600 mt-1">
+          Componi un preventivo per il cliente selezionando l'offerta e il prezzo
+        </p>
+      </div>
+
+      <Card className="p-6">
+        <QuoteBuilderForm clients={clientsData} offerMacros={offersData} />
+      </Card>
+    </div>
+  );
+}