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/dashboard.ts

@@ -3,6 +3,7 @@ import prisma from "../../config/database";
 import { requireAuth } from "../../middleware/auth";
 import { success } from "../../utils/response";
 import { localTimeStr } from "../../utils/date";
+import { toCzk } from "../../services/exchange-rates";
 
 export default async function dashboardRoutes(
   fastify: FastifyInstance,
@@ -206,10 +207,13 @@ export default async function dashboardRoutes(
           }),
         ),
         unpaid_count: unpaidCount,
-        revenue_czk:
-          revenueByCurrency["CZK"] != null
-            ? Math.round(revenueByCurrency["CZK"] * 100) / 100
-            : null,
+        revenue_czk: await (async () => {
+          let total = 0;
+          for (const [cur, amount] of Object.entries(revenueByCurrency)) {
+            total += await toCzk(Math.round(amount * 100) / 100, cur);
+          }
+          return Math.round(total * 100) / 100;
+        })(),
       };
       result.unpaid_invoices = unpaidCount;
     }

src/routes/admin/invoices-pdf.ts

@@ -5,6 +5,8 @@ import { requirePermission } from "../../middleware/auth";
 import { localDateCzStr } from "../../utils/date";
 import { nasFinancialsManager } from "../../services/nas-financials-manager";
 import { htmlToPdf } from "../../utils/html-to-pdf";
+import { getRate } from "../../services/exchange-rates";
+import { localDateStr } from "../../utils/date";
 
 /* ── Helpers ─────────────────────────────────────────────────────── */
 
@@ -358,9 +360,12 @@ export default async function invoicesPdfRoutes(
         // QR generation failed — leave empty
       }
 
-      // VAT recapitulation (always in CZK)
+      // VAT recapitulation (always in CZK — Czech tax requirement)
       const isForeign = currency.toUpperCase() !== "CZK";
-      const cnbRate = 1.0; // Skip CNB rate conversion
+      const issueDateStr = invoice.issue_date
+        ? localDateStr(new Date(invoice.issue_date))
+        : undefined;
+      const cnbRate = isForeign ? await getRate(currency, issueDateStr) : 1.0;
       const vatRates = [21, 12, 0];
       const vatRecap: Array<{
         rate: number;
@@ -1007,6 +1012,17 @@ ${indentCSS}
       <tbody>
         ${vatRecapHtml}
       </tbody>
+      ${
+        isForeign
+          ? `<tfoot>
+        <tr>
+          <td colspan="4" style="font-size:0.7em; color:#666; padding-top:6px; text-align:left;">
+            Přepočet kurzem ČNB ke dni ${formatDate(invoice.issue_date)}: 1 ${escapeHtml(currency)} = ${cnbRate.toFixed(3).replace(".", ",")} CZK
+          </td>
+        </tr>
+      </tfoot>`
+          : ""
+      }
     </table>
   </div>
 

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,
       });