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/lib/quote-actions.ts

@@ -0,0 +1,114 @@
+"use server";
+
+import { db } from "@/db";
+import { quotes, quote_items, clients, offer_micros, offer_phases } from "@/db/schema";
+import { createQuoteSchema } from "@/lib/quote-validators";
+import { eq } from "drizzle-orm";
+import { nanoid } from "nanoid";
+
+// Fetch offer with all phases and services for preview
+export async function getOfferWithPhases(offerMicroId: string) {
+  const [micro] = await db
+    .select()
+    .from(offer_micros)
+    .where(eq(offer_micros.id, offerMicroId))
+    .limit(1);
+
+  if (!micro) return null;
+
+  const phases = await db
+    .select()
+    .from(offer_phases)
+    .where(eq(offer_phases.micro_id, offerMicroId));
+
+  return {
+    ...micro,
+    phases,
+  };
+}
+
+// Server action: create quote with validation
+export async function createQuote(input: unknown) {
+  try {
+    // Validate input
+    const validated = createQuoteSchema.parse(input);
+
+    // Verify client exists
+    const [client] = await db
+      .select()
+      .from(clients)
+      .where(eq(clients.id, validated.client_id))
+      .limit(1);
+
+    if (!client) {
+      return {
+        success: false,
+        error: "Cliente non trovato",
+      };
+    }
+
+    // Verify offer exists
+    const [offer] = await db
+      .select()
+      .from(offer_micros)
+      .where(eq(offer_micros.id, validated.offer_micro_id))
+      .limit(1);
+
+    if (!offer) {
+      return {
+        success: false,
+        error: "Offerta non trovata",
+      };
+    }
+
+    // Generate unique token (nanoid 21 chars = ~122 bits entropy)
+    const token = nanoid(21);
+
+    // Convert accepted_total to numeric for DB storage
+    const totalAmount = parseFloat(validated.accepted_total);
+
+    // Create quote (atomic transaction)
+    const [insertedQuote] = await db
+      .insert(quotes)
+      .values({
+        client_id: validated.client_id,
+        offer_micro_id: validated.offer_micro_id,
+        token,
+        state: "draft",
+        accepted_total: totalAmount.toString(),
+      })
+      .returning();
+
+    if (!insertedQuote) {
+      return {
+        success: false,
+        error: "Errore nel salvataggio del preventivo",
+      };
+    }
+
+    // Return success with public link
+    const publicLink = `/quote/${token}`;
+
+    return {
+      success: true as const,
+      quote: insertedQuote,
+      token: token as string,
+      publicLink: publicLink as string,
+    };
+  } catch (error) {
+    const message = error instanceof Error ? error.message : "Errore sconosciuto";
+
+    // Check if it's a Zod validation error
+    if (message.includes("validation")) {
+      return {
+        success: false,
+        error: "Dati non validi. Controlla i campi obbligatori.",
+      };
+    }
+
+    return {
+      success: false,
+      error: message,
+    };
+  }
+}