Universal Agent Architecture v3.0.0

Major architectural change implementing Anthropic's recommendation:
"Don't Build Agents, Build Skills Instead"

Changes:
- 88 agent classes → 1 UniversalAgent
- Dynamic skill loading (106 skills)
- Parallel execution preserved via WorkerPool
- Circuit breaker for Human-in-the-Loop safety
- Checkpoint/resume for recovery
- 9 core skills created
- 30-50% token reduction expected

New API endpoints:
- POST /agents/universal/invoke
- POST /agents/oneshot/invoke

Breaking: Old agent classes still work but Universal Agent is now preferred.