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

@@ -3,7 +3,10 @@ import { beforeAll, describe, expect, it } from 'vitest';
 import { db } from '@/lib/db';
 import { documentTemplates } from '@/lib/db/schema/documents';
 import { clientAddresses, clientContacts, clients as clientsTable } from '@/lib/db/schema/clients';
-import { interests as interestsTable } from '@/lib/db/schema/interests';
+import {
+  interests as interestsTable,
+  interestBerths as interestBerthsTable,
+} from '@/lib/db/schema/interests';
 import { getMergeFields, resolveTemplate } from '@/lib/services/document-templates';
 
 import { makeBerth, makeClient, makeCompany, makePort, makeYacht } from '../helpers/factories';
@@ -44,12 +47,22 @@ async function insertInterest(args: {
       portId: args.portId,
       clientId: args.clientId,
       yachtId: args.yachtId ?? null,
-      berthId: args.berthId ?? null,
       pipelineStage: args.pipelineStage ?? 'open',
       leadCategory: args.leadCategory ?? null,
       notes: args.notes ?? null,
     })
     .returning();
+  // Plan §3.4: legacy interest.berth_id was replaced by the
+  // interest_berths junction. Tests that pass berthId now materialise a
+  // primary junction row alongside the interest.
+  if (args.berthId) {
+    await db.insert(interestBerthsTable).values({
+      interestId: row!.id,
+      berthId: args.berthId,
+      isPrimary: true,
+      isSpecificInterest: true,
+    });
+  }
   return row!;
 }
 
@@ -299,10 +312,15 @@ describe('resolveTemplate — company-owned yacht', () => {
         portId: port.id,
         clientId: client.id,
         yachtId: yacht.id,
-        berthId: berth.id,
         pipelineStage: 'open',
       })
       .returning();
+    await db.insert(interestBerthsTable).values({
+      interestId: interest!.id,
+      berthId: berth.id,
+      isPrimary: true,
+      isSpecificInterest: true,
+    });
 
     const [tmpl] = await db
       .insert(documentTemplates)
@@ -385,11 +403,16 @@ describe('resolveTemplate — legacy fallback (no interestId)', () => {
         portId: port.id,
         clientId: client.id,
         yachtId: null,
-        berthId: berth.id,
         pipelineStage: 'open',
         leadCategory: 'casual',
       })
       .returning();
+    await db.insert(interestBerthsTable).values({
+      interestId: interest!.id,
+      berthId: berth.id,
+      isPrimary: true,
+      isSpecificInterest: true,
+    });
 
     const [tmpl] = await db
       .insert(documentTemplates)