feat(eoi-generate): Include-yacht toggle to omit Section 3 when yacht is a placeholder

EoiGenerateDialog gains an inline "Include on EOI" checkbox in the
Section 3 header (renders only when ctx.yacht is set; defaults ON so
existing behaviour is unchanged). When OFF, the generate-and-sign POST
flips includeYachtDetails=false on the body; service blanks
eoiContext.yacht before either pathway runs:

- Documenso template payload: buildDocumensoPayload reads no yacht so
  yacht.* and owner.* merge fields ship empty. Existing template tolerates
  blanks per the "left blank if absent" copy.
- In-app PDF fill (pdf-lib): generateEoiPdfFromTemplate sees no yacht so
  AcroForm field writes for the yacht block are skipped.

Persists the rep's choice in the document-create audit log
(metadata.includeYachtDetails) so an audit trail records explicit opt-outs
even though documents has no JSONB metadata column today.

ft/m unit toggle in the Section 3 header now hides when Include is OFF
(unit choice is meaningless without yacht details).

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

src/lib/validators/document-templates.ts

@@ -109,6 +109,14 @@ export const generateAndSignSchema = generateSchema.extend({
    *  EOI's Length/Width/Draft formValues. The drawer's toggle drives this;
    *  server defaults to the yacht's `lengthUnit` column when omitted. */
   dimensionUnit: z.enum(['ft', 'm']).optional(),
+  /** Optional Section 3 (yacht details) inclusion. Defaults to true when a
+   *  yacht is linked. Rep can flip OFF in the dialog to blank out yacht.*
+   *  + owner.* merge fields even though a yacht is on file — used when the
+   *  yacht is a placeholder, multi-berth deals where yacht-specific dims
+   *  don't apply, or the client explicitly asked for the section to stay
+   *  off the document. Persisted in `documents.metadata.includeYachtDetails`
+   *  for audit. */
+  includeYachtDetails: z.boolean().optional(),
   /** Phase 3b/3-follow-up - optional per-field overrides applied at generation. */
   overrides: z
     .object({