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/admin/components/AttendanceShiftTable.tsx

@@ -87,7 +87,7 @@ function renderProjectCell(record: AttendanceRecord): React.ReactNode {
           }
           return (
             <span
-              key={log.id || i}
+              key={log.id ?? i}
               className="admin-badge"
               style={{
                 fontSize: "0.7rem",
@@ -95,7 +95,10 @@ function renderProjectCell(record: AttendanceRecord): React.ReactNode {
                 background: isActive ? "var(--accent-light)" : undefined,
               }}
             >
-              {log.project_name || `#${log.project_id}`} {durationValid ? `(${h}:${String(m).padStart(2, "0")}h${isActive ? " \u25B8" : ""})` : "—"}
+              {log.project_name || `#${log.project_id}`}{" "}
+              {durationValid
+                ? `(${h}:${String(m).padStart(2, "0")}h${isActive ? " \u25B8" : ""})`
+                : "—"}
             </span>
           );
         })}
@@ -257,4 +260,3 @@ export default function AttendanceShiftTable({
     </div>
   );
 }
-