security: fix all Medium findings from FLAWS_REPORT audit

- Auth: TOTP replay protection with counter tracking, constant-time
  backup code comparison, atomic lockout increment, per-token logout
- Invoices/PDFs: net-based VAT calculation, dangerous URL scheme
  stripping in cleanQuillHtml, orders-pdf error handling
- Orders: reject item changes on status transition, cascading
  delete cleanup, take:1 with orderBy
- Projects: atomic rename collision handling, MIME/extension
  validation, empty customer name rejection
- Attendance: Czech public holiday awareness in frontend fund
  calculation, leave_hours 0 handling, invalid date NaN guard,
  bounded per-month queries in workfund
- Users/Admin: profile audit logging + password validation, session
  revocation guard, session ID validation, dashboard DB aggregation,
  soft-deleted record protection in scope templates
- Frontend: FormField label linkage, Pagination ARIA, error
  handling in OrderConfirmationModal, 401 propagation, GPS emoji
  hidden from screen readers, table sort state fix, geolocation
  race/abort cleanup, Leaflet popup DOM safety, Vehicles toggleActive
  minimal body, CompanySettings ref mutation fix, OfferDetail unlock
  abort, AttendanceBalances combined fetches
- Utils: env validation, Puppeteer concurrency mutex, invoice alert
  cron cleanup on shutdown, body limit alignment, TOTP error logging,
  trustProxy from env, symlink rejection, rate cache Map usage

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

src/utils/totp.ts

@@ -2,7 +2,10 @@ import * as OTPAuthLib from "otpauth";
 import { decrypt } from "./encryption";
 
 export const OTPAuth = {
-  verify(encryptedSecret: string, code: string): boolean {
+  verify(
+    encryptedSecret: string,
+    code: string,
+  ): { valid: boolean; counter: number | null } {
     try {
       const secret = decrypt(encryptedSecret);
       const totp = new OTPAuthLib.TOTP({
@@ -12,9 +15,14 @@ export const OTPAuth = {
         period: 30,
       });
       const delta = totp.validate({ token: code, window: 1 });
-      return delta !== null;
-    } catch {
-      return false;
+      if (delta === null) {
+        return { valid: false, counter: null };
+      }
+      const currentCounter = Math.floor(Date.now() / 1000 / 30);
+      return { valid: true, counter: currentCounter + delta };
+    } catch (err) {
+      console.error("TOTP verification error:", err);
+      return { valid: false, counter: null };
     }
   },
 };