refactor(interests): migrate callers to interest_berths junction + drop berth_id

Phase 2b of the berth-recommender refactor (plan §3.4). Every caller of
the legacy `interests.berth_id` column now reads / writes through the
`interest_berths` junction via the helper service introduced in Phase 2a;
the column itself is dropped in a final migration.

Service-layer changes
- interests.service: filter `?berthId=X` becomes EXISTS-against-junction;
  list enrichment uses `getPrimaryBerthsForInterests`; create/update/
  linkBerth/unlinkBerth all dispatch through the junction helpers, with
  createInterest's row insert + junction write sharing a single transaction.
- clients / dashboard / report-generators / search: leftJoin chains pivot
  through `interest_berths` filtered by `is_primary=true`.
- eoi-context / document-templates / berth-rules-engine / portal /
  record-export / queue worker: read primary via `getPrimaryBerth(...)`.
- interest-scoring: berthLinked is now derived from any junction row count.
- dedup/migration-apply + public interest route: write a primary junction
  row alongside the interest insert when a berth is provided.

API contract preserved: list/detail responses still emit `berthId` and
`berthMooringNumber`, derived from the primary junction row, so frontend
consumers (interest-form, interest-detail-header) need no changes.

Schema + migration
- Drop `interestsRelations.berth` and `idx_interests_berth`.
- Replace `berthsRelations.interests` with `interestBerths`.
- Migration 0029_puzzling_romulus drops `interests.berth_id` + the index.
- Tests that previously inserted `interests.berthId` now seed a primary
  junction row alongside the interest.

Verified: vitest 995 passing (1 unrelated pre-existing flake in
maintenance-cleanup.test.ts), tsc clean.

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

src/lib/services/document-templates.ts

@@ -27,6 +27,7 @@ import { buildDocumensoPayload, getPortEoiSigners } from '@/lib/services/documen
 import { generateEoiPdfFromTemplate } from '@/lib/pdf/fill-eoi-form';
 import { MERGE_FIELDS, type MergeFieldCatalog } from '@/lib/templates/merge-fields';
 import { buildEoiContext } from '@/lib/services/eoi-context';
+import { getPrimaryBerth } from '@/lib/services/interest-berths.service';
 import { sendEmail } from '@/lib/email';
 import type {
   CreateTemplateInput,
@@ -374,15 +375,16 @@ export async function resolveTemplate(
         ? new Date(interest.dateContractSigned).toLocaleDateString('en-GB')
         : '';
       // Derive berth number from the interest when berthId wasn't passed and
-      // the EOI path didn't already populate it.
-      if (!eoiContextLoaded && interest.berthId && !context.berthId) {
-        const interestBerth = await db.query.berths.findFirst({
-          where: eq(berths.id, interest.berthId),
-        });
-        if (interestBerth) {
-          tokenMap['{{interest.berthNumber}}'] = interestBerth.mooringNumber;
+      // the EOI path didn't already populate it. Resolves through the
+      // interest_berths junction (plan §3.4) - the legacy interest.berth_id
+      // column has been removed.
+      const interestPrimaryBerth =
+        !eoiContextLoaded && !context.berthId ? await getPrimaryBerth(interest.id) : null;
+      if (!eoiContextLoaded && interestPrimaryBerth?.berthId && !context.berthId) {
+        if (interestPrimaryBerth.mooringNumber) {
+          tokenMap['{{interest.berthNumber}}'] = interestPrimaryBerth.mooringNumber;
           if (!tokenMap['{{berth.mooringNumber}}']) {
-            tokenMap['{{berth.mooringNumber}}'] = interestBerth.mooringNumber;
+            tokenMap['{{berth.mooringNumber}}'] = interestPrimaryBerth.mooringNumber;
           }
         } else {
           tokenMap['{{interest.berthNumber}}'] ??= '';