feat: CNB exchange rates, multi-currency KPI stats, invoice PDF VAT in CZK

- ČNB exchange rate service with date-specific rates and caching
- Invoice/received invoice stats convert foreign currencies to CZK
- Dashboard revenue converts all currencies to CZK
- Invoice PDF: VAT recap table always in CZK with CNB rate footer
- Inline styles replaced with utility classes (step 4 cleanup)
- Spinner animation exempt from prefers-reduced-motion

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/routes/admin/received-invoices.ts

@@ -12,6 +12,7 @@ import {
   UpdateReceivedInvoiceSchema,
 } from "../../schemas/received-invoices.schema";
 import { nasFinancialsManager } from "../../services/nas-financials-manager";
+import { toCzk } from "../../services/exchange-rates";
 
 const VALID_STATUSES = ["unpaid", "paid"] as const;
 const ALLOWED_SORT_FIELDS = [
@@ -108,12 +109,15 @@ export default async function receivedInvoicesRoutes(
           }));
       };
 
-      const sumCzk = (
+      const sumCzk = async (
         invs: typeof monthInvoices,
         field: "amount" | "vat_amount",
       ) => {
         let total = 0;
-        for (const inv of invs) total += Number(inv[field]) || 0;
+        for (const inv of invs) {
+          const amount = Number(inv[field]) || 0;
+          total += await toCzk(amount, inv.currency);
+        }
         return Math.round(total * 100) / 100;
       };
 
@@ -124,11 +128,11 @@ export default async function receivedInvoicesRoutes(
 
       return success(reply, {
         total_month: aggregateByCurrency(monthInvoices, "amount"),
-        total_month_czk: sumCzk(monthInvoices, "amount"),
+        total_month_czk: await sumCzk(monthInvoices, "amount"),
         vat_month: aggregateByCurrency(monthInvoices, "vat_amount"),
-        vat_month_czk: sumCzk(monthInvoices, "vat_amount"),
+        vat_month_czk: await sumCzk(monthInvoices, "vat_amount"),
         unpaid: aggregateByCurrency(allUnpaid, "amount"),
-        unpaid_czk: sumCzk(allUnpaid, "amount"),
+        unpaid_czk: await sumCzk(allUnpaid, "amount"),
         unpaid_count: allUnpaid.length,
         month_count: monthInvoices.length,
       });