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/dedup/migration-apply.ts

@@ -20,7 +20,7 @@ import { and, eq, inArray } from 'drizzle-orm';
 
 import { db } from '@/lib/db';
 import { clients, clientContacts, clientAddresses } from '@/lib/db/schema/clients';
-import { interests } from '@/lib/db/schema/interests';
+import { interests, interestBerths } from '@/lib/db/schema/interests';
 import { yachts } from '@/lib/db/schema/yachts';
 import { berths } from '@/lib/db/schema/berths';
 import { documents, documentSigners } from '@/lib/db/schema/documents';
@@ -306,7 +306,6 @@ async function applyInterest(
     .values({
       portId: opts.port.id,
       clientId,
-      berthId,
       yachtId,
       pipelineStage: planned.pipelineStage,
       leadCategory: planned.leadCategory,
@@ -326,6 +325,24 @@ async function applyInterest(
 
   if (!iRow) throw new Error('Interest insert returned no row');
 
+  // Plan §3.4: the legacy interests.berth_id column has been replaced by
+  // the interest_berths junction. Materialise the legacy single-berth link
+  // as a primary/specific row. is_in_eoi_bundle = true only when the
+  // legacy row already had a signed EOI.
+  if (berthId) {
+    await db
+      .insert(interestBerths)
+      .values({
+        interestId: iRow.id,
+        berthId,
+        isPrimary: true,
+        isSpecificInterest: true,
+        isInEoiBundle: planned.dateEoiSigned != null,
+        addedBy: opts.appliedBy ?? null,
+      })
+      .onConflictDoNothing({ target: [interestBerths.interestId, interestBerths.berthId] });
+  }
+
   await db.insert(migrationSourceLinks).values({
     sourceSystem: SOURCE_SYSTEM,
     sourceId: String(planned.sourceId),