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>

tests/unit/services/documenso-payload.test.ts

@@ -91,8 +91,9 @@ describe('buildDocumensoPayload', () => {
   });
 
   it('defaults missing yacht dimensions to empty strings', () => {
+    const baseYacht = makeContext().yacht!;
     const ctx = makeContext({
-      yacht: { ...makeContext().yacht, lengthFt: null, widthFt: null, draftFt: null },
+      yacht: { ...baseYacht, lengthFt: null, widthFt: null, draftFt: null },
     });
     const payload = buildDocumensoPayload(ctx, OPTIONS);
     expect(payload.formValues.Length).toBe('');
@@ -100,6 +101,16 @@ describe('buildDocumensoPayload', () => {
     expect(payload.formValues.Draft).toBe('');
   });
 
+  it('renders empty Section 3 when yacht and berth are not linked', () => {
+    const ctx = makeContext({ yacht: null, berth: null });
+    const payload = buildDocumensoPayload(ctx, OPTIONS);
+    expect(payload.formValues['Yacht Name']).toBe('');
+    expect(payload.formValues.Length).toBe('');
+    expect(payload.formValues.Width).toBe('');
+    expect(payload.formValues.Draft).toBe('');
+    expect(payload.formValues['Berth Number']).toBe('');
+  });
+
   it('formats empty address when client has no address', () => {
     const ctx = makeContext({ client: { ...makeContext().client, address: null } });
     const payload = buildDocumensoPayload(ctx, OPTIONS);