feat(07-02): extend PreparePanel with agentDownloadUrl/signedAt props and Signed download section

- Added agentDownloadUrl and signedAt to PreparePanelProps interface (optional, nullable)
- Destructure new props in function signature
- Added Signed status branch: green panel with signed timestamp and Download Signed PDF anchor
- Kept Sent/Viewed branch: gray read-only message
- Draft status: existing prepare form unchanged
- Download is a plain <a href> anchor — no fetch/onClick; browser follows link directly

teressa-copeland-homes/src/app/portal/(protected)/documents/[docId]/_components/PreparePanel.tsx

@@ -8,6 +8,8 @@ interface PreparePanelProps {
   defaultEmail: string;
   clientName: string;
   currentStatus: string;
+  agentDownloadUrl?: string | null;
+  signedAt?: Date | null;
 }
 
 function parseEmails(raw: string | undefined): string[] {
@@ -18,7 +20,7 @@ function isValidEmail(email: string): boolean {
   return /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email);
 }
 
-export function PreparePanel({ docId, defaultEmail, clientName, currentStatus }: PreparePanelProps) {
+export function PreparePanel({ docId, defaultEmail, clientName, currentStatus, agentDownloadUrl, signedAt }: PreparePanelProps) {
   const router = useRouter();
   const [recipients, setRecipients] = useState(defaultEmail ?? '');
   // Sync if defaultEmail arrives after initial render (streaming / hydration timing)
@@ -29,9 +31,51 @@ export function PreparePanel({ docId, defaultEmail, clientName, currentStatus }:
   const [loading, setLoading] = useState(false);
   const [result, setResult] = useState<{ ok: boolean; message: string } | null>(null);
 
+  if (currentStatus === 'Signed') {
+    return (
+      <div style={{ borderRadius: '0.5rem', border: '1px solid #D1FAE5', padding: '1rem', backgroundColor: '#F0FDF4' }}>
+        <p style={{ fontSize: '0.875rem', color: '#065F46', fontWeight: 600, marginBottom: '0.5rem' }}>
+          Document Signed
+        </p>
+        {signedAt && (
+          <p style={{ fontSize: '0.75rem', color: '#6B7280', marginBottom: '0.75rem' }}>
+            Signed on{' '}
+            {new Date(signedAt).toLocaleString('en-US', {
+              timeZone: 'America/Denver',
+              month: 'short',
+              day: 'numeric',
+              year: 'numeric',
+              hour: 'numeric',
+              minute: '2-digit',
+            })}
+          </p>
+        )}
+        {agentDownloadUrl ? (
+          <a
+            href={agentDownloadUrl}
+            style={{
+              display: 'inline-block',
+              padding: '0.5rem 1rem',
+              backgroundColor: '#1B2B4B',
+              color: '#FFFFFF',
+              borderRadius: '0.375rem',
+              fontSize: '0.875rem',
+              fontWeight: 500,
+              textDecoration: 'none',
+            }}
+          >
+            Download Signed PDF
+          </a>
+        ) : (
+          <p style={{ fontSize: '0.75rem', color: '#9CA3AF' }}>Signed PDF not available.</p>
+        )}
+      </div>
+    );
+  }
+
   if (currentStatus !== 'Draft') {
     return (
-      <div className="rounded-lg border border-gray-200 p-4 bg-gray-50 text-sm text-gray-500">
+      <div style={{ borderRadius: '0.5rem', border: '1px solid #E5E7EB', padding: '1rem', backgroundColor: '#F9FAFB', fontSize: '0.875rem', color: '#6B7280' }}>
         Document status is <strong>{currentStatus}</strong> — preparation is only available for Draft documents.
       </div>
     );