docs: complete project research synthesis

Synthesized findings from 4 parallel research agents into unified
SUMMARY.md with roadmap implications for Grid Guardian GNN-based
anomaly detection system.

Files:
- STACK.md (PyTorch Geometric, Kafka, Redis stack)
- FEATURES.md (self-play, GNN verification, uncertainty quantification)
- ARCHITECTURE.md (hybrid verifier, graph construction, real-time pipeline)
- PITFALLS.md (oversmoothing, mode collapse, evaluation validity)
- SUMMARY.md (executive summary with 6-phase roadmap structure)

Key findings:
- Stack: PyTorch Geometric + temporal extensions for 100K node SSEN graphs
- Architecture: Hybrid 3-layer cascade (physics → GNN → temporal)
- Critical pitfall: Mode collapse prevention via entropy-based diversity rewards

Research confidence: MEDIUM-HIGH (proven components, novel integration)
Ready for requirements definition phase.

Author: vmehtacode