Add assignment engine, FCM, WebSockets, city gate, and internal APIs

- internal/assignment: GEORADIUS miler assignment with retry/escalation,
  customer-side provider scoring, FCM notifications on assign
- internal/notify: Firebase Admin SDK (FCM) client initialisation
- internal/ws: WebSocket handlers for live parcel tracking and
  customer↔miler chat
- middlewares: city gate (pincode prefix validation), internal API key
  auth, WebSocket JWT auth
- controllers: InternalNotify + InternalReassign for machine-to-machine
  calls; pricing helpers wired into CreateCustomerBooking and CreateCRMBooking
- routes: /internal/*, /ws/bookings/:id/track, /ws/bookings/:id/chat
- models/users, models/doormile_pricing: new fields for device tokens,
  assignment state, pricing bands
- seed_data.sql: initial pricing seed rows

.env and Firebase service-account JSON intentionally excluded.

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

models/doormile_pricing.go

@@ -16,6 +16,8 @@ type DoormilePricing struct {
 	Minprice            float64    `json:"min_price" gorm:"column:min_price;not null"`
 	Maxprice            float64    `json:"max_price" gorm:"column:max_price;not null"`
 	Currency            string     `json:"currency" gorm:"column:currency;default:INR"`
+	Providercompany     string     `json:"provider_company" gorm:"column:provider_company;default:Doormile"`
+	Reliabilityscore    float64    `json:"reliability_score" gorm:"column:reliability_score;default:5.0"`
 	Status              string     `json:"status" gorm:"column:status;default:Active"`
 	Createdat           time.Time  `json:"createdat" gorm:"column:createdat;default:CURRENT_TIMESTAMP"`
 	Updatedat           time.Time  `json:"updatedat" gorm:"column:updatedat;default:CURRENT_TIMESTAMP"`