Add local development support for setup and proof runs

[mariaKt]

This PR re-enables local development after the switch from the mir-semantics submodule to kompass.

• setup.sh --local-dev: install kmir and kompass from local paths (via KMIR_LOCAL and KOMPASS_LOCAL env vars)
  instead of pinned remote version
• run-proofs.sh: detect local-dev mode and include local commit hashes in proof directory names"

I also added a clean target for simpler rebuilding, since it would occur often for local development.

[dkcumming]

Nice, I don't have a chance to run it but it looks right!

[mariaKt]

I tested it locally myself

• with sequences of local builds in different commits to test the naming, and sometimes with errors so that they would fail, to make sure that the changes were picked up.
• local and non local, to test the use of the marker.