PAB to CTL in dUSD Spec

[epiro-ps]

Closes https://github.com/ArdanaLabs/dUSD/issues/377.

Other changes

Added traceability, authentication, and discoverability to vault implementation spec.

• [ ] The impure tests via nix run .#offchain:test were run and all are passing.
• [x] Where applicable, grammar, punctuation, and spelling within code and comments should be plausibly correct.
• [x] The issue(s) that the work is addressing should be linked in the PR description.
• [ ] Any significant changes beyond what's clear from the linked issue(s) are documented in the PR description