(feat) O3-5552: validate transition time to prevent negative wait duration

[Brijesh-0106]

Requirements

• This PR has a title that briefly describes the work done including
  the ticket number (feat) O3-5552 with conventional commit label.
• My work is based on the existing validation patterns used throughout
  the queue module — the error response structure mirrors other validation
  errors in QueueEntryTransitionRestController and uses the same
  APIException approach consistent with the rest of the codebase.
• My work does not yet include tests. This is my first contribution
  to this module and I plan to add tests in a follow-up PR after
  receiving initial feedback on the implementation.

Summary

The queue-entry transition endpoint accepted future dates as valid transition dates, which caused incorrect queue state — a transition could be recorded as happening in the future, making queue metrics and wait times unreliable for clinical staff.
This PR adds a server-side validation check that rejects any transition request where the provided transitionDate is in the future.
Changes made:

Added a future date check in QueueEntryTransitionRestController.transitionQueueEntry() immediately after the transition date is resolved
If the provided date is after the current server time, an APIException is thrown with a descriptive message including the invalid date value
Validation runs before any queue state is modified, so no partial transitions can occur

Example error response:

json{
  "error": {
    "message": "Transition cannot be in the future"
  }
}

Jira: O3-5552

Screenshots

No change in UI

Related Issue

https://openmrs.atlassian.net/browse/O3-5552