Security: Add Smart Contract Emergency Pause Mechanism with Governance

[Smartdevs17]

Context

Smart contract vulnerabilities discovered post-deployment require immediate action. Without a pause mechanism, funds are at risk during the fix window.

Current Limitation/Problem

There is no emergency pause mechanism for smart contracts. If a vulnerability is discovered, there is no way to halt operations while a fix is deployed.

Expected Outcome

An emergency pause mechanism for all critical contracts (Soroban + EVM) with multi-sig governance, automatic unpause timeout, and transparent audit logging.

Acceptance Criteria

• Inherit OpenZeppelin Pausable (EVM) and implement equivalent for Soroban
• Pause/unpause functions restricted to multi-sig governance
• Critical functions check whenNotPaused modifier
• Automatic unpause after configurable timeout (max 72 hours)
• Emergency pause by single guardian (with timelock for unpause)
• Events: Paused, Unpaused, PauseProposed, PauseGuardianChanged
• Dashboard showing current pause state per contract
• Pause state visible in contract explorer
• Test suite: all critical functions revert when paused
• Documentation: pause/unpause procedure for operators

Technical Scope

• contracts/evm/security/Pausable.sol - EVM pause mechanism
• contracts/soroban/security/src/ - Soroban pause implementation
• Guardian role management with multi-sig
• backend/src/services/contracts/pause-manager.ts - backend integration
• Frontend: /admin/contracts - pause state dashboard
• Edge cases: partial pause (some functions), guardian key compromise, cross-chain pause sync

[olathedev]

@olathedev has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hello maintainer i would love to work on this issue.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @olathedev to this issue.