Add payments with TDS, invoice detail view and filterable History (Phase E2)

- Migration M8 adds payments (cash, TDS, mode, reference). Payment status is derived, never stored: unpaid, partially paid, paid, or overdue. Overpayment is rejected, TDS counts toward settling, and only issued invoices accept payments. list_invoices and get_invoice carry the paid, TDS and balance summary.
- New invoice detail view: archived-PDF preview, payments list, Record payment modal, Export, Duplicate (as a draft), Re-render and Cancel. An invoice with payments cannot be cancelled until they are deleted.
- History gets search, status, financial-year, month and client filters, sortable columns, pagination, footer totals and an FY summary. Cancelled invoices are excluded from totals. The per-row archive-status calls are gone; archiving is on the detail page.
- Rust tests for payments and the list summary; vitest for fiscal-year, money, filter and duplicate helpers.

PDF output and fingerprint goldens are unchanged. The new UI has not been run in a webview yet.

src/App.tsx

@@ -6,6 +6,7 @@ import { AppShell, type AppView } from "./components/AppShell";
 import Onboarding from "./views/Onboarding";
 import NewInvoice from "./views/NewInvoice";
 import InvoiceHistory from "./views/InvoiceHistory";
+import InvoiceDetail from "./views/InvoiceDetail";
 import Clients from "./views/Clients";
 import { ToastProvider, useToast } from "./components/ToastProvider";
 import AppSettings from "./views/AppSettings";
@@ -24,6 +25,9 @@ function AppInner() {
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState<string | null>(null);
   const [view, setView] = useState<AppView>("new");
+  const [detailId, setDetailId] = useState<number | null>(null);
+  // A draft made by "Duplicate" that the New invoice form should open once it is shown.
+  const [openDraftId, setOpenDraftId] = useState<number | null>(null);
 
   const refreshSettings = useCallback(async () => {
     try {
@@ -104,10 +108,31 @@ function AppInner() {
           onSettingsChange={refreshSettings}
           active={view === "new"}
           onActivate={() => setView("new")}
+          openDraftId={openDraftId}
+          onDraftOpened={() => setOpenDraftId(null)}
         />
         <div hidden={view !== "invoices"}>
-          <InvoiceHistory settings={settings} active={view === "invoices"} />
+          <InvoiceHistory
+            settings={settings}
+            active={view === "invoices"}
+            onOpen={(id) => {
+              setDetailId(id);
+              setView("invoice");
+            }}
+          />
         </div>
+        {view === "invoice" && detailId !== null ? (
+          <InvoiceDetail
+            key={detailId}
+            invoiceId={detailId}
+            settings={settings}
+            onBack={() => setView("invoices")}
+            onDuplicated={(draftId) => {
+              setOpenDraftId(draftId);
+              setView("new");
+            }}
+          />
+        ) : null}
         <div hidden={view !== "clients"}>
           <Clients active={view === "clients"} />
         </div>