Fix Docker signup, refresh docs, and improve blank invoice flow.

Parse DISABLE_SIGNUPS and related env booleans correctly for Compose string values, and derive auth trustedOrigins from BETTER_AUTH_URL. Rewrite README and architecture docs with the git.soconnor.dev remote and accurate deployment guidance. Allow zero-line-item draft invoices with validation when sending email.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/app/dashboard/invoices/new/page.tsx

@@ -1,7 +1,13 @@
 "use client";
 
+import { Suspense } from "react";
+
 import InvoiceForm from "~/components/forms/invoice-form";
 
 export default function NewInvoicePage() {
-  return <InvoiceForm />;
+  return (
+    <Suspense fallback={null}>
+      <InvoiceForm />
+    </Suspense>
+  );
 }

src/app/dashboard/invoices/page.tsx

@@ -3,7 +3,7 @@ import { Suspense } from "react";
 import { api, HydrateClient } from "~/trpc/server";
 import { Button } from "~/components/ui/button";
 import { PageHeader } from "~/components/layout/page-header";
-import { Plus, Upload } from "lucide-react";
+import { FileText, Plus, Upload } from "lucide-react";
 import { InvoicesDataTable } from "./_components/invoices-data-table";
 import { DataTableSkeleton } from "~/components/data/data-table";
 
@@ -28,6 +28,12 @@ export default async function InvoicesPage() {
             <span>Import CSV</span>
           </Link>
         </Button>
+        <Button asChild variant="outline" className="hover-lift shadow-sm">
+          <Link href="/dashboard/invoices/new?blank=1">
+            <FileText className="mr-2 h-5 w-5" />
+            <span>Blank invoice</span>
+          </Link>
+        </Button>
         <Button asChild variant="default" className="hover-lift shadow-md">
           <Link href="/dashboard/invoices/new">
             <Plus className="mr-2 h-5 w-5" />