Add Turso/Vercel deployment configuration

- Updated database connection to support Turso auth token
- Added vercel.json with bun build configuration
- Updated environment schema for production deployment
- Added new features and components for production readiness

src/app/dashboard/invoices/[id]/_components/unified-invoice-page.tsx

@@ -0,0 +1,26 @@
+"use client";
+
+import { InvoiceView } from "~/components/invoice-view";
+import { InvoiceForm } from "~/components/invoice-form";
+
+interface UnifiedInvoicePageProps {
+  invoiceId: string;
+  mode: string;
+}
+
+export function UnifiedInvoicePage({
+  invoiceId,
+  mode,
+}: UnifiedInvoicePageProps) {
+  return (
+    <div>
+      {/* Always render InvoiceForm to preserve state, but hide when in view mode */}
+      <div className={mode === "edit" ? "block" : "hidden"}>
+        <InvoiceForm invoiceId={invoiceId} />
+      </div>
+
+      {/* Show InvoiceView only when in view mode */}
+      {mode === "view" && <InvoiceView invoiceId={invoiceId} />}
+    </div>
+  );
+}