feat(11-02): preparePdf() gains agentSignatureData param and embeds at agent-sig fields

- Add optional agentSignatureData: string | null = null as 5th parameter
- Import PDFImage from @cantoo/pdf-lib for typed agentSigImage variable
- Embed PNG once before field loop, store as agentSigImage
- Replace agent-signature stub with drawImage at field.x/y/width/height

teressa-copeland-homes/src/lib/pdf/prepare-document.ts

@@ -1,4 +1,4 @@
-import { PDFDocument, StandardFonts, rgb } from '@cantoo/pdf-lib';
+import { PDFDocument, PDFImage, StandardFonts, rgb } from '@cantoo/pdf-lib';
 import { readFile, writeFile, rename } from 'node:fs/promises';
 import type { SignatureFieldData } from '@/lib/db/schema';
 import { getFieldType } from '@/lib/db/schema';
@@ -23,12 +23,19 @@ export async function preparePdf(
   destPath: string,
   textFields: Record<string, string>,
   sigFields: SignatureFieldData[],
+  agentSignatureData: string | null = null,
 ): Promise<void> {
   const pdfBytes = await readFile(srcPath);
   const pdfDoc = await PDFDocument.load(pdfBytes);
   const helvetica = await pdfDoc.embedFont(StandardFonts.Helvetica);
   const pages = pdfDoc.getPages();
 
+  // Embed agent signature image once — reused across all agent-sig fields
+  let agentSigImage: PDFImage | null = null;
+  if (agentSignatureData) {
+    agentSigImage = await pdfDoc.embedPng(agentSignatureData);
+  }
+
   // Track which text field entries were successfully written via AcroForm so that
   // the fallback text stamp only shows entries that were NOT already embedded.
   const acroFilledKeys = new Set<string>();
@@ -136,7 +143,15 @@ export async function preparePdf(
       // No marker drawn — text content is provided via textFillData (separate pipeline)
 
     } else if (fieldType === 'agent-signature') {
-      // Skip — agent signature handled by Phase 11; no placeholder drawn here
+      if (agentSigImage) {
+        page.drawImage(agentSigImage, {
+          x: field.x,
+          y: field.y,
+          width: field.width,
+          height: field.height,
+        });
+      }
+      // If no signature saved: the prepare route guards against this with 422 before calling preparePdf
     }
   }