Universal Agent V3.1 - Skill Runtime Integration

Major Features:
- Semantic skill discovery (pgvector)
- Dual-phase discovery (pre/post Ex Nihilo)
- Unified HITL (pipeline + skill level)
- Hybrid token budget (3 levels)
- Tier-gated access control
- 6 execution types via ExecutionRouter

New Components:
- src/integration/* - V3 integration layer
- Migration 009 - V3 analytics tables

Backward Compatible:
- V2 endpoints still available
- File-based skills as fallback