Fix 9 backend bugs: pricing, zones, geocoding, device tokens, assignment retry

- pricingid null: lookupDoormilePrice now returns matched rule ID; wired to BookingServiceOption.Pricingid
- Zone rename: Interstate→Regional, OtherState→National throughout (code + DB migrated)
- Zone from pincodes: CheckPrice now accepts pickup_pincode+delivery_pincode and auto-resolves zone
- Delivery geocoding: pincodeToLatLon() maps 3-digit prefix to city coords when lat/lon are 0
- Device tokens: device_token field added to PinVerify DTOs; saved on both customer and miler login
- Assignment retry: RejectMilerAssignment now re-triggers AssignCustomerMiler/AssignCRMMiler immediately
- Provider empty B2C: defaults to Doormile when no pricing provider row matches
- City gate 422→400: StatusUnprocessableEntity corrected to StatusBadRequest
- Miler GPS 0,0: WS tracking falls back to MilerProfile DB coords when Redis key is expired

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

internal/ws/tracking.go

@@ -113,6 +113,17 @@ func TrackingHandler(c *websocket.Conn) {
 			milerUserID := *booking.Assignedmileruserid
 			lat, lon, gpsOk := readMilerGPS(milerUserID)
 
+			// Redis key expired or not yet set — fall back to last known DB coords.
+			if !gpsOk {
+				var mp models.MilerProfile
+				if db.DB.Where("userid = ?", milerUserID).First(&mp).Error == nil &&
+					(mp.Currentlatitude != 0 || mp.Currentlongitude != 0) {
+					lat = mp.Currentlatitude
+					lon = mp.Currentlongitude
+					gpsOk = true
+				}
+			}
+
 			frame := trackingFrame{
 				Status:    booking.Status,
 				MilerName: milerName(milerUserID),