chore(i18n): drop legacy free-text country/nationality columns

Test-data only — no production migration needed (per earlier decision).
Schema is now ISO-only; readers convert ISO codes to localized names where
human-readable output is required (EOI documents, invoices, portal).

Migration 0016 drops:
  - clients.nationality
  - companies.incorporation_country
  - client_addresses.{state_province, country}
  - company_addresses.{state_province, country}

Code paths that previously read free-text values now read the ISO column
and pass through `getCountryName()` / `getSubdivisionName()` for rendering.
Document templates ({{client.nationality}}), portal client view, EOI/
reservation-agreement contexts, and invoice billing addresses all updated.

Public yacht-interest endpoint (/api/public/interests) drops the legacy
fields from its insert path and writes ISO codes only. The Zod validators
no longer accept the legacy fields — older website builds posting raw
'incorporationCountry' / 'country' / 'stateProvince' will get 400s.
Server-side phone normalization is unchanged.

Seed data updated to use ISO codes (GB/FR/ES/GR/SE/IT/GH/MC/PA), spread
across continents to keep test fixtures realistic.

Test assertions updated to match the new render shape (e.g.
'United States' not 'US', 'California' not 'CA').

Vitest: 741 -> 741 (unchanged count; assertions updated, no new tests).

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

tests/integration/document-templates-eoi.test.ts

@@ -126,7 +126,7 @@ describe('resolveTemplate — EOI scope tokens', () => {
     const port = await makePort();
     const client = await makeClient({
       portId: port.id,
-      overrides: { fullName: 'Alice Client', nationality: 'US', source: 'referral' },
+      overrides: { fullName: 'Alice Client', nationalityIso: 'US', source: 'referral' },
     });
     await db.insert(clientContacts).values([
       { clientId: client.id, channel: 'email', value: 'alice@example.com', isPrimary: true },
@@ -137,7 +137,7 @@ describe('resolveTemplate — EOI scope tokens', () => {
       portId: port.id,
       streetAddress: '1 Main St',
       city: 'Town',
-      country: 'US',
+      countryIso: 'US',
       isPrimary: true,
     });
 
@@ -321,7 +321,7 @@ describe('resolveTemplate — legacy fallback (no interestId)', () => {
     const port = await makePort();
     const client = await makeClient({
       portId: port.id,
-      overrides: { fullName: 'Carol NoInterest', nationality: 'UK', source: 'website' },
+      overrides: { fullName: 'Carol NoInterest', nationalityIso: 'GB', source: 'website' },
     });
     await db.insert(clientContacts).values({
       clientId: client.id,
@@ -349,7 +349,8 @@ describe('resolveTemplate — legacy fallback (no interestId)', () => {
 
     expect(resolved).toContain('Hello Carol NoInterest');
     expect(resolved).toContain('carol@example.com');
-    expect(resolved).toContain('from UK');
+    // Nationality renders the localized name from the ISO code (GB -> United Kingdom).
+    expect(resolved).toContain('from United Kingdom');
     expect(resolved).toContain('src=website');
   });