Updated `Authorize` attributes in multiple controllers to use
`AuthenticationSchemes = AuthScheme.Sender` instead of
`Policy = AuthPolicy.Sender`, reflecting a shift in the
authentication mechanism.
Added detailed logging in `EnvelopeReceiverController` to handle
cases where stored procedures return `OUT_SUCCESS=false`,
providing contextual information for debugging.
Removed unused SQL code and declarations in
`EnvelopeReceiverController` to improve code readability and
maintainability.