Add access control matrix and Foundry coverage

[modelsbridgeaicom-ship-it]

/claim #63

Summary

• Adds a focused Foundry access-control matrix suite covering unauthorized callers for role-gated, owner-gated, and minter-hook entrypoints.
• Covers privileged success paths for stablecoin freeze/unfreeze, reserve admin, compliance updates, minter admin, depeg guard tuning, BurnToll routing, and Lucidly reserve operations.
• Adds docs/access-control-matrix.md with the external/public function matrix and focused gas report table.

Validation

• git diff --check
• forge test --match-path forge-test/AccessControlMatrix.t.sol --gas-report

[abhicris]

🤖 Audit verdict: safe

Pure documentation and test addition with no production code changes, no secrets, no suspicious dependencies or network calls, and proper test structure using standard Foundry patterns.

Audited by the kcolbchain PR pipeline. See pipeline docs.

[abhicris]

Welcome to kcolbchain, @modelsbridgeaicom-ship-it — glad you're here. 🌱

Here's what happens from this PR:

1. Our automated review looks for obvious issues (tests, secrets, size) within a couple of hours.
2. If it's clean and CI passes, we merge without back-and-forth.
3. If we need changes, we'll leave a specific comment — not a generic nit. Push another commit and we re-review.

While you wait:

• Run the repo's tests locally (see the repo README.md).
• Keep the PR scoped to one concern — bigger PRs land slower.
• Don't commit tokens or .env contents.

What happens after your first merge

• You're listed on https://kcolbchain.com/contributors/ (opt-out anytime via data/contributors-optout.txt).
• At 2+ merged PRs you're a Regular; at 5+ you're a Fellow — Fellows are the pool we invite first for paid research, partner-org gigs, and grant-funded work. Details: https://kcolbchain.com/docs/org-contribution-policy.html
• Looking for what to pick up next? https://kcolbchain.com/invitations/ lists open help-wanted / good-first-issue across every kcolbchain repo.

Thanks for writing the code. We're building this to last.