docs: finalize Phase 4 & 5 implementation updates and project TODO list status

feat(browser-skill): Implement Phase 4 Browser Automation foundations & fix GitBucket utility formatting

feat(distributed-agent): Refactor to Skill-Based Architecture, implement Robust Task Management & finalize Roadmap

feat(agent): support PERMISSIVE vs STRICT sandbox modes #7

feat(agent): complete phase 2 security, identity, and observability #6

feat(agent): implement phase 1 gRPC POC and update architecture docs #5

Update Cortex Agent Node Architecture Plan with User Technical Feedback

Draft: Cortex Agent Node Architecture and Implementation Plan