* ecdsa signature proof

* use the library-provided default circuit

* small reorg

Co-authored-by: Srinath Setty <srinath@microsoft.com>

use a default implementation for step circuit

* support multiple iterations of MinRoot per Nova step

* small edits to println

* fix declaration

* add the MinRoot VDF example

* optimize a bit

* optimization and cleanup

* clippy

* add examples to CI

* use inbuilt pow_vartime