feat: add cloud agent deployment package for Phase 3 completion

Setup infrastructure:
- scripts/setup-cloud-agent-env.sh: Complete Ubuntu 24.04 environment setup
  - Go 1.25.2 installation with version checking
  - Python 3.11+ installation via deadsnakes PPA if needed
  - All dev tools: containerd, Docker, kubectl, OpenTofu, Pulumi, OPA, protoc
  - Automatic repository cloning and dependency installation
  - 366 lines, production-ready

Agent prompts:
- prompts/agent-1-event-streaming.md: Real-time event streaming (1,100+ lines)
  - Complete event bus architecture
  - WebSocket server implementation guide
  - CLI watch command specifications
  - Integration with orchestrator/agents/policy
  - Tests and documentation requirements

- prompts/agent-2-rest-api.md: Complete REST API (1,000+ lines)
  - Full REST API implementation guide
  - OpenAPI 3.0 specification structure
  - All endpoints documented (runs, agents, findings, policies)
  - Authentication/RBAC/rate limiting/CORS
  - Comprehensive testing requirements

Deployment guide:
- CLOUD-AGENTS-READY.md: Complete deployment documentation
  - 3 parallel agents ready for cloud deployment
  - No coordination needed (isolated branches/containers)
  - Setup instructions and troubleshooting
  - Monitoring and success criteria
  - 1-2 week timeline to Phase 3 completion

Purpose:
Complete Phase 3 from 60% to 100% via parallel cloud-based agents.
Each agent works in isolated Ubuntu 24.04 containers with their own worktrees.

Target: v0.4.0 release with complete Phase 3 features