Handle Event Ordering and Duplicate Processing

[DakotaCondos]

As a system maintainer,
I want the Function App to handle duplicate and out-of-order robot events,
so that the Cosmos DB bot read model remains accurate.

Acceptance Criteria

• Given the same event is delivered more than once
  When the Function App processes the duplicate
  Then the duplicate does not create incorrect state or inventory changes.

• Given an older telemetry event arrives after a newer telemetry event
  When timestamps are compared
  Then the older telemetry event is ignored for state updates.

• Given an older stock event arrives after a newer stock event
  When timestamps are compared
  Then the older stock event is ignored for inventory updates.

• Given a status event is newer than the current status timestamp
  When the Function App processes it
  Then the bot status is updated.

• Given event processing fails
  When the Function App cannot update Cosmos DB
  Then the failure is logged and the event can be retried or investigated.