feat(vat)!: remove VAT entirely from offers, orders and issued orders

Accounting rule: nabidky, objednavky (incl. confirmation PDF) and objednavky
vydane are NOT tax documents - VAT belongs only on invoices. Per user
decision this is a FULL removal including DB columns.

- migration: DROP orders.vat_rate/apply_vat, issued_orders.vat_rate/apply_vat,
  issued_order_items.vat_rate, quotations.vat_rate/apply_vat (applied to
  dev + test DBs)
- services: net-only totals everywhere (computeIssuedOrderTotals(items) ->
  {total}; enrichOrder/enrichQuotation net; per-currency list totals net)
- PDFs (offers, order confirmation, issued order): no VAT columns/summary,
  single 'Celkem bez DPH' / 'Total excl. VAT' total, note under totals:
  'Ceny jsou uvedeny bez DPH. DPH bude uctovano dle platnych predpisu.';
  duplicate Cena/Celkem column merged (desc width 56%); orders-pdf render
  extracted as exported renderOrderConfirmationHtml for testability
- frontend: Uplatnit DPH checkboxes, VAT selects and per-item VAT columns
  removed from OfferDetail/OrderDetail/IssuedOrderDetail/
  OrderConfirmationModal/ReceivedOrders manual-create; list footers read
  'Celkem bez DPH'; invoice-from-order prefill now takes the company default
  VAT (invoice decides its own VAT)
- tests: suites reworked to net math; new pdf-vat-note.test.ts pins the
  exact cs+en note text and VAT-free layout on all three PDFs

Invoices and received invoices keep their VAT handling unchanged.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/admin/pages/ReceivedOrders.tsx

@@ -184,8 +184,6 @@ export default function OrdersReceived({
     customer_id: "",
     customer_order_number: "",
     currency: "CZK",
-    vat_rate: "21",
-    apply_vat: true,
     scope_title: "",
     scope_description: "",
     notes: "",
@@ -219,8 +217,6 @@ export default function OrdersReceived({
       customer_id: "",
       customer_order_number: "",
       currency: "CZK",
-      vat_rate: "21",
-      apply_vat: true,
       scope_title: "",
       scope_description: "",
       notes: "",
@@ -255,8 +251,6 @@ export default function OrdersReceived({
           fd.append("customer_id", createForm.customer_id);
         fd.append("customer_order_number", createForm.customer_order_number);
         fd.append("currency", createForm.currency);
-        fd.append("vat_rate", createForm.vat_rate);
-        fd.append("apply_vat", createForm.apply_vat ? "1" : "0");
         fd.append("scope_title", createForm.scope_title);
         fd.append("scope_description", createForm.scope_description);
         fd.append("notes", createForm.notes);
@@ -274,8 +268,6 @@ export default function OrdersReceived({
               : null,
             customer_order_number: createForm.customer_order_number,
             currency: createForm.currency,
-            vat_rate: createForm.vat_rate,
-            apply_vat: createForm.apply_vat,
             scope_title: createForm.scope_title,
             scope_description: createForm.scope_description,
             notes: createForm.notes,
@@ -571,7 +563,7 @@ export default function OrdersReceived({
               fontSize: "0.9rem",
             }}
           >
-            <span>Celkem:</span>
+            <span>Celkem bez DPH:</span>
             <Box
               component="span"
               sx={{ fontWeight: 700, color: "text.primary" }}
@@ -669,19 +661,6 @@ export default function OrdersReceived({
               />
             </Field>
           </Box>
-          <Box sx={{ flex: "1 1 200px" }}>
-            <Field label="Sazba DPH (%)">
-              <TextField
-                type="number"
-                inputMode="numeric"
-                value={createForm.vat_rate}
-                onChange={(e) =>
-                  setCreateForm({ ...createForm, vat_rate: e.target.value })
-                }
-                slotProps={{ htmlInput: { min: 0 } }}
-              />
-            </Field>
-          </Box>
         </Box>
 
         <Box sx={{ display: "flex", gap: 2, flexWrap: "wrap" }}>
@@ -757,12 +736,6 @@ export default function OrdersReceived({
           />
         </Field>
 
-        <CheckboxField
-          label="Účtovat DPH"
-          checked={createForm.apply_vat}
-          onChange={(v) => setCreateForm({ ...createForm, apply_vat: v })}
-        />
-
         <CheckboxField
           label="Vytvořit propojený projekt"
           checked={createForm.create_project}