docs(01): research GNN verifier foundation

Phase 1: GNN Verifier Foundation
- Standard stack: PyTorch Geometric 2.7.0, GATv2Conv
- Architecture: 3-layer GAT with residual + LayerNorm
- Temporal: 1D-Conv encoder for time-window features
- Pitfalls: oversmoothing, edge_index format, isolated nodes

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: vmehtacode