Use Cosmos Bot Read Model in Order Service Candidate Selection

[DakotaCondos]

As the Order Service API,
I want to use the Cosmos DB bot read model to select candidate bots for new orders,
so that orders can be routed to bots that appear available and stocked without depending directly on the simulator runtime for normal candidate reads.

Acceptance Criteria

• Given a customer submits an order
  When the Order Service API evaluates candidate bots
  Then it reads bot availability, location, and inventory from the Cosmos DB bots container.

• Given multiple bots can fulfill the order
  When the Order Service API selects a target bot
  Then it chooses a bot based on defined selection rules such as availability, stock, distance, or priority.

• Given the Order Service API selects a target bot
  When it creates the order assignment
  Then it publishes the assignment to the robot-input Event Hub.

• Given the readable bot state may be slightly behind the simulator
  When the simulator receives the order assignment
  Then the simulator performs final stock and availability validation before accepting the order.

• Given the simulator accepts, queues, or rejects the order
  When the response event is published
  Then downstream processing updates the readable bot representation as needed.