[EPIC] Complete RBAC System Documentation

[kevalyq]

Sub-Issues & Work Plan

• ADR-005: Document RBAC Core Design Decisions #142 ADR-005: Document RBAC Core Design Decisions
• Central RBAC Architecture Documentation #143 Central RBAC Architecture Documentation
• Developer Guides: Direct Permissions & Temporal Roles #144 Developer Guides: Direct Permissions & Temporal Roles
• README Update & Phase 4 Sub-Issue References #145 README Update & Phase 4 Sub-Issue References

[github-actions]

✅ This issue has been added to the SecPal Feature Roadmap with status: 💡 Ideas

New idea - needs discussion and evaluation

Status Flow:
💡 Ideas → 💬 Discussion → 📥 Backlog → 📋 Planned → 🚧 In Progress → 👀 In Review → ✅ Done

Note: Ideas that won't be implemented should be moved to 🚫 Won't Do with a reason.