Fix forge-std remapping for invariant CI

[MyTH-zyxeon]

Summary

• fixes the Forge remapping introduced with the invariant tests
• points forge-std/ imports at the installed Foundry library under lib/forge-std/src/
• keeps the change scoped to foundry.toml

Why

main and #45 currently fail forge test because forge-std/StdInvariant.sol resolves through the local forge-std/ shim directory, which only contains Test.sol. The workflow already installs foundry-rs/forge-std, so the remapping should target that installed package instead.

Validation

• GitHub Actions should rerun the existing forge workflow on this one-line config change.

[abhicris]

🤖 Audit verdict: safe

Routine Foundry configuration fix updating a circular/broken remapping to the standard library path; no code execution, secrets, or supply-chain risk.

Audited by the kcolbchain PR pipeline. See pipeline docs.

[abhicris]

Merged — thanks, @MyTH-zyxeon. That's 9 merged PRs to kcolbchain now.

You're a Fellow — when paid research, partner-org work, or grant milestones come up, you're in the first invite pool.

Next-up issues across the org: https://kcolbchain.com/invitations/