feat(db): m:m interest_berths junction + role flags

Introduces the multi-berth interest model from plan §3.1: a junction
between interests and berths with three role flags so the same berth
can be linked as the primary deal target, an EOI-bundle inclusion,
or a "just exploring" link without conflating semantics.

- 0028 schema migration creates interest_berths with the unique
  partial index "≤1 primary per interest", a unique compound on
  (interest_id, berth_id), and indexes for the public-map "under
  offer" lookup (where is_specific_interest=true).
- Same migration adds desired_length_ft / desired_width_ft /
  desired_draft_ft to interests for the recommender.
- Same migration runs the Phase 2 data migration: every interest
  with a non-null berth_id gets one junction row marked
  is_primary=true, is_specific_interest=true, and is_in_eoi_bundle =
  (eoi_status='signed'). Pre-flight check halts on dangling FKs
  (§14.3 critical case).
- New service src/lib/services/interest-berths.service.ts owns reads
  + writes of the junction. getPrimaryBerth / getPrimaryBerthsForInterests
  feed list pages; upsertInterestBerth demotes the prior primary in
  the same transaction so the unique index is never violated.
- interests.berth_id stays in place this commit so existing callers
  keep working; Phase 2b migrates them onto the helper service and a
  later migration drops the column.

53 dev rows seeded into the junction; tests still green at 996.

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

src/lib/db/schema/interests.ts

@@ -1,6 +1,18 @@
-import { pgTable, text, boolean, integer, timestamp, primaryKey, index } from 'drizzle-orm/pg-core';
+import {
+  pgTable,
+  text,
+  boolean,
+  integer,
+  numeric,
+  timestamp,
+  primaryKey,
+  index,
+  uniqueIndex,
+} from 'drizzle-orm/pg-core';
+import { sql } from 'drizzle-orm';
 import { ports } from './ports';
 import { clients } from './clients';
+import { berths } from './berths';
 
 // Pipeline stages: open, details_sent, in_communication, eoi_sent, eoi_signed, deposit_10pct, contract_sent, contract_signed, completed
 
@@ -47,6 +59,11 @@ export const interests = pgTable(
     /** When the outcome was decided. Lets us age 'how long ago did we lose'. */
     outcomeAt: timestamp('outcome_at', { withTimezone: true }),
     notes: text('notes'),
+    /** Recommender inputs - imperial; resolver treats nulls as "no constraint"
+     *  on that axis, with a banner prompting the rep to add the missing dim. */
+    desiredLengthFt: numeric('desired_length_ft'),
+    desiredWidthFt: numeric('desired_width_ft'),
+    desiredDraftFt: numeric('desired_draft_ft'),
     archivedAt: timestamp('archived_at', { withTimezone: true }),
     createdAt: timestamp('created_at', { withTimezone: true }).notNull().defaultNow(),
     updatedAt: timestamp('updated_at', { withTimezone: true }).notNull().defaultNow(),
@@ -62,6 +79,59 @@ export const interests = pgTable(
   ],
 );
 
+/**
+ * Many-to-many junction between interests and berths.
+ *
+ * Replaces the old single-berth `interests.berth_id` column. Each row
+ * carries three role flags so a rep can model "actively pitching this
+ * berth" vs "covered by the EOI bundle but not pitched" vs "primary
+ * berth for the deal" independently:
+ *
+ *   - is_primary           : at most one row per interest is the primary;
+ *                            templates / forms / "the berth for this deal"
+ *                            semantics resolve through this row.
+ *   - is_specific_interest : true = berth shows as "Under Offer" on the
+ *                            public map. false = legal/EOI-only link.
+ *   - is_in_eoi_bundle     : covered by the interest's EOI signature.
+ *
+ * EOI bypass: when the interest has a signed primary EOI but a specific
+ * berth in the bundle still needs its own EOI, a rep records the bypass
+ * reason here.
+ */
+export const interestBerths = pgTable(
+  'interest_berths',
+  {
+    id: text('id')
+      .primaryKey()
+      .$defaultFn(() => crypto.randomUUID()),
+    interestId: text('interest_id')
+      .notNull()
+      .references(() => interests.id, { onDelete: 'cascade' }),
+    berthId: text('berth_id')
+      .notNull()
+      .references(() => berths.id, { onDelete: 'restrict' }),
+    isPrimary: boolean('is_primary').notNull().default(false),
+    isSpecificInterest: boolean('is_specific_interest').notNull().default(true),
+    isInEoiBundle: boolean('is_in_eoi_bundle').notNull().default(false),
+    eoiBypassReason: text('eoi_bypass_reason'),
+    eoiBypassedBy: text('eoi_bypassed_by'),
+    eoiBypassedAt: timestamp('eoi_bypassed_at', { withTimezone: true }),
+    addedBy: text('added_by'),
+    addedAt: timestamp('added_at', { withTimezone: true }).notNull().defaultNow(),
+    notes: text('notes'),
+  },
+  (table) => [
+    uniqueIndex('idx_ib_interest_berth').on(table.interestId, table.berthId),
+    uniqueIndex('idx_ib_one_primary')
+      .on(table.interestId)
+      .where(sql`${table.isPrimary} = true`),
+    index('idx_ib_berth').on(table.berthId),
+    index('idx_ib_specific')
+      .on(table.berthId)
+      .where(sql`${table.isSpecificInterest} = true`),
+  ],
+);
+
 export const interestNotes = pgTable(
   'interest_notes',
   {
@@ -96,3 +166,5 @@ export type Interest = typeof interests.$inferSelect;
 export type NewInterest = typeof interests.$inferInsert;
 export type InterestNote = typeof interestNotes.$inferSelect;
 export type NewInterestNote = typeof interestNotes.$inferInsert;
+export type InterestBerth = typeof interestBerths.$inferSelect;
+export type NewInterestBerth = typeof interestBerths.$inferInsert;