feat(api): add staff order booking contract and shift timeline alias

docs/BACKEND/API_GUIDES/V2/mobile-frontend-implementation-spec.md

@@ -4,7 +4,7 @@ This is the shortest path for frontend to implement the v2 mobile clients agains
 
 Base URL:
 
-- `https://krow-api-v2-933560802882.us-central1.run.app`
+- `https://krow-api-v2-e3g6witsvq-uc.a.run.app`
 
 Use this doc together with:
 
@@ -30,7 +30,10 @@ Important consequences:
 
 - `GET /staff/shifts/open` returns open shift-role opportunities.
 - `POST /staff/shifts/:shiftId/apply` must send the `roleId` from that response.
-- `GET /client/orders/view` is the timeline/read model for the client app.
+- `GET /staff/orders/available` returns grouped order opportunities for atomic booking.
+- `POST /staff/orders/:orderId/book` must send the `roleId` from that response.
+- `GET /client/shifts/scheduled` is the canonical timeline/read model for the client app.
+- `GET /client/orders/view` is a deprecated compatibility alias.
 - `POST /client/orders/:orderId/edit` and `POST /client/orders/:orderId/cancel` only affect future shifts.
 
 ## 3) Auth implementation
@@ -122,7 +125,8 @@ Dispatch-priority rule:
 
 ### Orders
 
-- `GET /client/orders/view`
+- `GET /client/shifts/scheduled`
+- `GET /client/orders/view` deprecated alias
 - `GET /client/orders/:orderId/reorder-preview`
 - `POST /client/orders/one-time`
 - `POST /client/orders/recurring`
@@ -175,13 +179,17 @@ Rapid-order flow:
 
 ### Find shifts
 
+- `GET /staff/orders/available`
+- `POST /staff/orders/:orderId/book`
 - `GET /staff/shifts/open`
 - `POST /staff/shifts/:shiftId/apply`
 
 Rule:
 
-- send the `roleId` from the open-shifts response
-- this is the concrete `shift_roles.id`
+- send the `roleId` from the order-available response when booking an order
+- this `roleId` is the role catalog id for grouped order booking
+- send the `roleId` from the open-shifts response only when applying to one shift
+- that route still uses the concrete `shift_roles.id`
 
 ### My shifts