Security & Compliance Platform Enhancements

## Description

Build out the security and compliance platform features — access control, evidence tracking, vendor risk, and third-party integrations.

## Scope

- [ ] Advanced access control & permissions (RBAC, team-based access)
- [ ] Third-party compliance tool integrations (API connectors)
- [ ] Vendor risk assessment & supply chain security scoring
- [ ] Automated control assessment & testing engine
- [ ] Attestation management & evidence tracking (extends existing EvidenceService)

## Consolidates

#75, #77, #83, #89, #90

Start by reading the existing EvidenceService and the consolidated issues #75, #77, #83, #89, and #90 to understand the prior requirements. The work is complete only when the listed access control, integrations, vendor risk, automated assessment, attestation, and evidence-tracking capabilities have defined and implemented behavior.

由索引模型根據 Issue 內容生成。