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/orders.ts

@@ -88,12 +88,10 @@ export default async function ordersRoutes(
       const attachment = await getOrderAttachment(id);
       if (!attachment) return error(reply, "Příloha nenalezena", 404);
 
+      const safeFilename = attachment.filename.replace(/[\r\n"\\/]/g, "");
       return reply
         .type("application/pdf")
-        .header(
-          "Content-Disposition",
-          `inline; filename="${attachment.filename}"`,
-        )
+        .header("Content-Disposition", `inline; filename="${safeFilename}"`)
         .send(attachment.data);
     },
   );
@@ -209,6 +207,7 @@ export default async function ordersRoutes(
       const body = manualParsed.data;
 
       const result = await createOrder(body);
+      if ("error" in result) return error(reply, result.error!, result.status!);
 
       await logAudit({
         request,