core: implement multi-sig admin for critical operations

[EmeditWeb]

Problem

All 5 contracts have a single admin key. If the
deployer private key is compromised, the entire
protocol can be drained. Critical operations like
setting parameters and upgrading contracts have
no multi-signature protection.

What To Build

1. Add multi-sig support to parameters-contract
2. Implement proposal system for critical ops
3. Apply to critical operations only

Files To Touch

• contracts/parameters-contract/src/lib.rs
• contracts/parameters-contract/src/types.rs
• All contract upgrade() functions

Acceptance Criteria

• Critical ops require 2-of-N signatures
• Proposals expire after 7 days
• Duplicate signatures rejected
• Non-critical ops unaffected
• Tests cover approval flow end to end

Mandatory Checks Before PR

• cargo build passes
• All tests pass
• PR references this issue

[Iwayemi-Kehinde]

I would like to work on this issue as I have reviewed the scope, I should have a PR Ready in 50 minutes.

[VeronicDev]

I am interested in working on this issue. I have experience with Rust and smart contract security and can implement a robust multi-signature approval system for critical protocol operations. My approach will include adding proposal creation and approval flows, enforcing a 2-of-N signature threshold, preventing duplicate approvals, implementing 7-day proposal expiration, and integrating multi-sig checks into upgrade and other critical functions while leaving non-critical operations unaffected. I will ensure comprehensive end-to-end tests are included and that all build and test requirements pass before submitting a PR linked to this issue.