feat(tenancies-renew-transfer): tenure-aware renewal + transfer actions

- renewTenancy service:
  - permanent / fee_simple / strata_lot → mutate-in-place (startDate
    moves forward, endDate may extend or null out)
  - fixed_term / seasonal → end the current row at its existing endDate
    + mint a successor with previousTenancyId chain. newEndDate required.
- transferTenancy service: end-and-spawn — end current row at
  transferDate, mint fresh active row with transferredFromTenancyId
  pointing back. New client + yacht cross-validated against port +
  ownership constraint (assertClientOwnsOrRepresentsYacht).
- POST /api/v1/tenancies/[id]/renew + /transfer routes gated on
  tenancies.manage + module-enabled.
- TenancyRenewDialog (tenure-aware copy explains in-place vs successor),
  TenancyTransferDialog (ClientPicker + YachtPicker with owner-scoped
  filter). Both mounted on tenancy-detail.tsx alongside Edit + End.
- Validators: renewTenancySchema + transferTenancySchema in
  src/lib/validators/tenancies.ts.

Verified: tsc clean, 1493/1493 vitest.

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

src/lib/validators/tenancies.ts

@@ -42,6 +42,31 @@ export const updateTenancySchema = z
   .refine((d) => Object.keys(d).length > 0, { message: 'At least one field must be provided' });
 export type UpdateTenancyInput = z.infer<typeof updateTenancySchema>;
 
+/** Renewal input. For permanent-class tenancies the existing row is
+ *  mutated in place; for fixed_term / seasonal the existing row is
+ *  ended at `previousEndDate` and a fresh row is minted with
+ *  previousTenancyId pointing back. */
+export const renewTenancySchema = z.object({
+  /** New start date for the renewal window (or the mutated row when permanent). */
+  newStartDate: z.coerce.date(),
+  /** New end date — required for fixed_term / seasonal; optional when permanent. */
+  newEndDate: z.coerce.date().optional(),
+  /** Optional notes appended to the successor / mutated row. */
+  notes: z.string().optional(),
+});
+export type RenewTenancyInput = z.infer<typeof renewTenancySchema>;
+
+/** Transfer input — hand a berth's active tenancy to a new client/yacht
+ *  pair. The current row is ended, a fresh active row is minted with
+ *  transferredFromTenancyId pointing at the predecessor. */
+export const transferTenancySchema = z.object({
+  newClientId: z.string().min(1),
+  newYachtId: z.string().min(1),
+  transferDate: z.coerce.date(),
+  notes: z.string().optional(),
+});
+export type TransferTenancyInput = z.infer<typeof transferTenancySchema>;
+
 export const listTenanciesSchema = baseListQuerySchema.extend({
   status: z.enum(TENANCY_STATUSES).optional(),
   berthId: z.string().optional(),