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/search.service.ts

@@ -75,7 +75,9 @@ export async function search(portId: string, query: string): Promise<SearchResul
       LIMIT 10
     `),
 
-    // Interests: JOIN to clients and berths, ILIKE search
+    // Interests: JOIN to clients and primary-berth via interest_berths
+    // (plan §3.4 - the legacy interests.berth_id column has been replaced
+    // by the junction).
     db.execute<{
       id: string;
       full_name: string;
@@ -89,7 +91,9 @@ export async function search(portId: string, query: string): Promise<SearchResul
         i.pipeline_stage
       FROM interests i
       JOIN clients c ON i.client_id = c.id
-      LEFT JOIN berths b ON i.berth_id = b.id
+      LEFT JOIN interest_berths ib
+        ON ib.interest_id = i.id AND ib.is_primary = true
+      LEFT JOIN berths b ON ib.berth_id = b.id
       WHERE i.port_id = ${portId}
         AND i.archived_at IS NULL
         AND (