refactor: fix all Low findings from FLAWS_REPORT audit

- Auth: TOTP params from config, JWT error logging, audit log failure
  logging, replaced_by_hash validation on token rotation
- Invoices: remove dead VAT code, consistent PDF permissions,
  WebP magic-byte detection, deduped exchange-rate fetches
- Orders/Offers: multipart limit from config, use paginated() helper,
  payment method from DB in PDF
- Projects: verify project exists before creating note
- Attendance: action_type enum validation, consistent local-time
  shift_date construction, holiday attendance in work fund,
  trips.view permission on last-km query
- Users: paginated() helper usage, remove duplicate dashboard keys,
  parallel currency conversion, single hashToken implementation
- Frontend: memoized customInput, reliable print onload, modal prop
  standardization (isOpen), ConfirmModal type icons, id===0 key
  fallback, Login useCallback, CompanySettings ConfirmModal,
  Attendance timeout cleanup, Dashboard memoization, beforeunload
  dirty-state warnings on Invoice/Offer/Order detail
- Schema: invoice_alert_log timestamp, config/env comment on
  Date.prototype.toJSON override
- Utils: exchange-rate inflight dedup

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

src/utils/totp.ts

@@ -1,5 +1,6 @@
 import * as OTPAuthLib from "otpauth";
 import { decrypt } from "./encryption";
+import { config } from "../config/env";
 
 export const OTPAuth = {
   verify(
@@ -10,15 +11,15 @@ export const OTPAuth = {
       const secret = decrypt(encryptedSecret);
       const totp = new OTPAuthLib.TOTP({
         secret: OTPAuthLib.Secret.fromBase32(secret),
-        algorithm: "SHA1",
-        digits: 6,
-        period: 30,
+        algorithm: config.totp.algorithm,
+        digits: config.totp.digits,
+        period: config.totp.period,
       });
       const delta = totp.validate({ token: code, window: 1 });
       if (delta === null) {
         return { valid: false, counter: null };
       }
-      const currentCounter = Math.floor(Date.now() / 1000 / 30);
+      const currentCounter = Math.floor(Date.now() / 1000 / config.totp.period);
       return { valid: true, counter: currentCounter + delta };
     } catch (err) {
       console.error("TOTP verification error:", err);