security: fix all Critical and High findings from FLAWS_REPORT audit

- Auth: pessimistic locking on login tokens and refresh token rotation,
  backup code attempt counter, rate limiting verification
- Schema: unique constraints on business numbers, FK relations,
  unsigned/signed alignment, attendance duplicate prevention
- Invoices/PDFs: DOMPurify sanitization, bounded queries in stats
  and alerts, VAT rounding, Puppeteer error handling
- Orders/Offers: transactional parent+child creation, Zod NaN
  refinement, status enums, uniqueness checks
- Projects/Files: path traversal protection, streamed uploads,
  permission guards, query param validation
- Attendance/HR: duplicate checks, ownership validation, GPS
  restrictions, trip distance validation
- Frontend: modal lock reference counting, XSS escaping in print
  HTML, ref mutation fixes, accessibility attributes

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/routes/admin/quotations.ts

@@ -245,6 +245,8 @@ export default async function quotationsRoutes(
       if ("error" in parsed) return error(reply, parsed.error, 400);
 
       const quotation = await createOffer(parsed.data);
+      if ("error" in quotation)
+        return error(reply, quotation.error!, quotation.status!);
 
       await logAudit({
         request,
@@ -312,9 +314,13 @@ export default async function quotationsRoutes(
       // Delete PDF from NAS
       if (existing.quotation_number && existing.created_at) {
         const yr = new Date(existing.created_at).getFullYear();
-        nasOffersManager.deleteOfferPdf(
-          nasOffersManager.buildRelativePath(existing.quotation_number, yr),
-        );
+        try {
+          await nasOffersManager.deleteOfferPdf(
+            nasOffersManager.buildRelativePath(existing.quotation_number, yr),
+          );
+        } catch {
+          // Non-fatal: NAS delete may fail if file does not exist
+        }
       }
 
       await logAudit({