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>

tests/unit/services/eoi-context.test.ts

@@ -3,7 +3,13 @@ import { describe, it, expect } from 'vitest';
 import { buildEoiContext } from '@/lib/services/eoi-context';
 import { makePort, makeClient, makeCompany, makeBerth, makeYacht } from '../../helpers/factories';
 import { db } from '@/lib/db';
-import { interests, clientContacts, clientAddresses, companyAddresses } from '@/lib/db/schema';
+import {
+  interests,
+  interestBerths,
+  clientContacts,
+  clientAddresses,
+  companyAddresses,
+} from '@/lib/db/schema';
 import { ValidationError, NotFoundError } from '@/lib/errors';
 
 // ─── Helpers ──────────────────────────────────────────────────────────────────
@@ -21,10 +27,20 @@ async function insertInterest(args: {
       portId: args.portId,
       clientId: args.clientId,
       yachtId: args.yachtId ?? null,
-      berthId: args.berthId ?? null,
       pipelineStage: args.pipelineStage ?? 'open',
     })
     .returning();
+  // Plan §3.4: legacy interests.berth_id replaced by the junction. Tests
+  // that pass berthId materialise a primary junction row alongside the
+  // interest so getPrimaryBerth() resolves it during EOI context build.
+  if (args.berthId) {
+    await db.insert(interestBerths).values({
+      interestId: row!.id,
+      berthId: args.berthId,
+      isPrimary: true,
+      isSpecificInterest: true,
+    });
+  }
   return row!;
 }