feat: miler delivery-leg fixes — consignmentid, auto route sequencing, admin consignment status

Miler app P0 + contract gaps found in the live audit:

- GET /miler/bookings now returns consignmentid + consignmentstatus on every
  row (nullable), so the app can call deliver/skip/start-delivery straight from
  the list. /miler/assignments is the active-only queue, so this is the
  authoritative fix for stops that have moved onto the delivery leg.
- GET /miler/bookings now returns sequencedat per row: non-null means the
  console/optimizer fixed this stop's order and the app follows step exactly;
  null means no route assigned and the app may fall back to nearest-first.
- Route sequencing (internal/routing) now runs automatically after every
  assignment — customer auto-assign, express auto-assign, manual assign, and
  accept — via SequenceMilerStopsAsync (fire-and-forget, no-op below two active
  stops). Previously only hub batch-assign sequenced, so most riders saw step=0.
- GET /admin/bookings now surfaces the live consignmentstatus alongside the
  frozen booking status, so a Converted_To_Consignment booking can still show
  Out_for_Delivery / Delivered instead of a generic "Active".

Two-step hyperlocal flow (Arrived_At_Pickup, Collected_By_Miler, start-delivery)
stays gated behind MILER_COLLECTED_STATE_ENABLED (default off) until the app
ships; consignmentid/status, GET /miler/consignments/:id, stable error codes and
Idempotency-Key handling are unconditional and safe on the current app.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01WRaFH5hMRqmUQvVPQsyjZD

models/users.go

@@ -97,8 +97,8 @@ type MilerProfile struct {
 	// telemetry bridge it existed for was removed — but it is kept as a record
 	// of where each migrated rider came from, which is worth having during the
 	// cutover. Nil for riders created natively in Doormile.
-	Legacyuserid          *int       `json:"legacyuserid,omitempty" gorm:"column:legacyuserid;index"`
-	Defaultvehicletype    string     `json:"defaultvehicletype" gorm:"column:defaultvehicletype"`
+	Legacyuserid       *int   `json:"legacyuserid,omitempty" gorm:"column:legacyuserid;index"`
+	Defaultvehicletype string `json:"defaultvehicletype" gorm:"column:defaultvehicletype"`
 	// Address is the rider's home/base address, editable from the app's profile
 	// screen. App-only until now, so it had nowhere durable to land. Nullable/
 	// additive. (Email is not duplicated here — it lives on AppUser.Email, the