Function: transitionToYieldMode()

This function is an admin-controlled state change that closes the KYC phase and enables the Yield phase.

Branches and code coverage

Intended branches

• Update the _mode to OperationalMode.Yield.

  Test coverage

Negative behavior

• Non-admin callers, or calls outside the KYC phase or after the deposit window ends, revert.

  Negative test

Function call analysis

• None.