chore(deps): remove unused regorus yaml feature

[elezar]

Summary

Remove the unused yaml feature from regorus so openshell-supervisor-network no longer pulls deprecated YAML parser crates through the policy engine path. Replace prover fields that intentionally ignore unsupported policy sections with serde::de::IgnoredAny.

Related Issue

Refs #2018

Changes

• Removed yaml from the regorus feature list in openshell-supervisor-network.
• Updated Cargo.lock to reflect the removed regorus YAML feature.
• Replaced ignored prover YAML value fields with serde::de::IgnoredAny.

Testing

• mise exec -- cargo check -p openshell-supervisor-network
• mise exec -- cargo test -p openshell-supervisor-network opa
• mise exec -- cargo check -p openshell-prover
• mise exec -- cargo test -p openshell-prover
• git diff --check
• mise run pre-commit passes (attempted; local macOS Command Line Tools cannot resolve the SDK, and xcrun --show-sdk-path fails with unable to find sdk: 'macosx'; failure occurs while compiling the temporary fake-forward-process in openshell-cli integration tests)

Checklist

• Follows Conventional Commits
• Commits are signed off (DCO)