feat(eoi): align prerequisites with EOI document structure

Match the gate to the actual EOI's structure (Section 2 vs Section 3) so
the rep can generate the document the moment they have what they need —
and not before.

  Required (Section 2 — top paragraph):
    - Client name
    - Client primary email
    - Client primary address

  Optional (Section 3 — left blank when absent):
    - Linked yacht (name, dimensions)
    - Linked berth (mooring number)

Previously the dialog blocked generation unless yacht AND berth were both
linked, which was overzealous — early-stage EOIs are routinely sent before
a specific berth is pinned down.

  - eoi-context.ts: yacht and berth are now nullable in the returned
    context. The hard ValidationError is now driven by the EOI's Section
    2 fields (name/email/address) rather than yacht/berth presence. The
    owner block falls back to the interest's client when no yacht is
    linked, so signing parties remain resolvable.

  - documenso-payload.ts + fill-eoi-form.ts: Section 3 form values
    render as empty strings when yacht or berth are absent, so the
    rendered PDF leaves those template inputs blank.

  - document-templates.ts: yacht.* and berth.* tokens fall back to
    empty strings; the legacy-fallback catch handler also recognises
    the new "missing required client details" error.

  - interests.service.ts: getInterestById now also returns
    `clientPrimaryEmail` and `clientHasAddress` so the Documents tab
    can compute the EOI prerequisites checklist client-side without an
    extra fetch.

  - eoi-generate-dialog.tsx: prereqs split into two groups visually —
    Required (with red ✗ when missing) and Optional (with grey – when
    absent). The Generate button only requires the Required block to
    pass. A small amber banner surfaces when Required is incomplete so
    the rep knows where to add the missing data.

Tests: 835/835 pass. Replaces the obsolete "throws on missing yacht/
berth" tests with parity coverage for the new behaviour ("builds a
valid context when yacht/berth missing", "throws when client email/
address missing"). Adds a payload test for the empty-Section-3 case.

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

src/lib/services/documenso-payload.ts

@@ -128,11 +128,13 @@ export function buildDocumensoPayload(
       Name: context.client.fullName,
       Email: context.client.primaryEmail ?? '',
       Address: formatAddress(context.client.address),
-      'Yacht Name': context.yacht.name,
-      Length: context.yacht.lengthFt ?? '',
-      Width: context.yacht.widthFt ?? '',
-      Draft: context.yacht.draftFt ?? '',
-      'Berth Number': context.berth.mooringNumber,
+      // Yacht + berth are optional EOI fields; when not linked, render as
+      // empty strings so the corresponding template inputs stay blank.
+      'Yacht Name': context.yacht?.name ?? '',
+      Length: context.yacht?.lengthFt ?? '',
+      Width: context.yacht?.widthFt ?? '',
+      Draft: context.yacht?.draftFt ?? '',
+      'Berth Number': context.berth?.mooringNumber ?? '',
       Lease_10: false,
       Purchase: true,
     },