feat(eoi): in-app pathway fills the same source PDF as Documenso

When the in-app pathway is used for EOI templates, we now load the same
source PDF that the Documenso template uploads and fill its AcroForm
fields with values from EoiContext via pdf-lib. Field names mirror the
Documenso template's formValues keys exactly (Name, Email, Address,
Yacht Name, Length, Width, Draft, Berth Number + Lease_10 / Purchase
checkboxes), so both pathways produce equivalent legal documents — only
the renderer differs.

The form is left interactive (not flattened) so a recipient can still
adjust values before signing. Non-EOI templates (welcome letters,
acknowledgments, etc.) keep using the existing HTML→pdfme path.

Adds:
- pdf-lib direct dep
- src/lib/pdf/fill-eoi-form.ts — load + fill helpers, EOI_TEMPLATE_PDF_PATH
  env override
- assets/ + README documenting the expected source PDF
- next.config outputFileTracingIncludes so the asset is bundled in the
  standalone build

Tests: 8 new (4 fill-form unit + 2 source-PDF route + 2 fallback);
645/645 green.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/lib/pdf/fill-eoi-form.ts

@@ -0,0 +1,101 @@
+import { promises as fs } from 'node:fs';
+import path from 'node:path';
+
+import { PDFDocument } from 'pdf-lib';
+
+import type { EoiContext } from '@/lib/services/eoi-context';
+
+/**
+ * Source PDF for the in-app EOI pathway. Must contain AcroForm fields whose
+ * names match the Documenso template's `formValues` keys exactly:
+ *
+ *   Text:     Name, Email, Address, Yacht Name, Length, Width, Draft,
+ *             Berth Number
+ *   Checkbox: Lease_10, Purchase
+ *
+ * See assets/eoi-template/README.md for full details and the field mapping
+ * doc at docs/eoi-documenso-field-mapping.md for the canonical list.
+ */
+const DEFAULT_EOI_TEMPLATE_PATH = path.join(process.cwd(), 'assets', 'eoi-template.pdf');
+
+function eoiTemplatePath(): string {
+  return process.env.EOI_TEMPLATE_PDF_PATH ?? DEFAULT_EOI_TEMPLATE_PATH;
+}
+
+export async function loadEoiTemplatePdf(): Promise<Uint8Array> {
+  const filePath = eoiTemplatePath();
+  try {
+    return await fs.readFile(filePath);
+  } catch (err) {
+    throw new Error(
+      `EOI source PDF not found at ${filePath}. Drop the same PDF used by the Documenso template (with AcroForm fields: Name, Email, Address, Yacht Name, Length, Width, Draft, Berth Number, Lease_10, Purchase) at this path, or override via EOI_TEMPLATE_PDF_PATH. Original error: ${(err as Error).message}`,
+    );
+  }
+}
+
+function formatAddress(address: EoiContext['client']['address']): string {
+  if (!address) return '';
+  return [address.street, address.city, address.country].filter(Boolean).join(', ');
+}
+
+function setText(form: ReturnType<PDFDocument['getForm']>, name: string, value: string): void {
+  try {
+    form.getTextField(name).setText(value);
+  } catch {
+    // Field absent or wrong type — skip silently so a slightly different PDF
+    // template still produces output. Missing field issues surface in QA, not
+    // at runtime as a 500.
+  }
+}
+
+function setCheckbox(
+  form: ReturnType<PDFDocument['getForm']>,
+  name: string,
+  checked: boolean,
+): void {
+  try {
+    const cb = form.getCheckBox(name);
+    if (checked) cb.check();
+    else cb.uncheck();
+  } catch {
+    // See comment in setText.
+  }
+}
+
+/**
+ * Fills the AcroForm fields of the EOI source PDF with values drawn from
+ * EoiContext. Field names mirror the Documenso template `formValues` keys so
+ * a single source PDF can serve both pathways.
+ *
+ * The form is left interactive (not flattened) so a recipient can still tweak
+ * fields if needed before signing.
+ */
+export async function fillEoiFormFields(
+  pdfBytes: Uint8Array,
+  context: EoiContext,
+): Promise<Uint8Array> {
+  const doc = await PDFDocument.load(pdfBytes);
+  const form = doc.getForm();
+
+  setText(form, 'Name', context.client.fullName);
+  setText(form, 'Email', context.client.primaryEmail ?? '');
+  setText(form, 'Address', formatAddress(context.client.address));
+  setText(form, 'Yacht Name', context.yacht.name);
+  setText(form, 'Length', context.yacht.lengthFt ?? '');
+  setText(form, 'Width', context.yacht.widthFt ?? '');
+  setText(form, 'Draft', context.yacht.draftFt ?? '');
+  setText(form, 'Berth Number', context.berth.mooringNumber);
+
+  setCheckbox(form, 'Purchase', true);
+  setCheckbox(form, 'Lease_10', false);
+
+  return doc.save();
+}
+
+/**
+ * Convenience: loads the source PDF from disk and returns the filled bytes.
+ */
+export async function generateEoiPdfFromTemplate(context: EoiContext): Promise<Uint8Array> {
+  const bytes = await loadEoiTemplatePdf();
+  return fillEoiFormFields(bytes, context);
+}