docs: Add cognitive frontier implementation plans (#80)

Add comprehensive implementation documentation for two frontier
capabilities extending ruvector-mincut integration:

1. Federated Strange Loops (federated-strange-loops.md)
   - Multiple autonomous graph systems observing each other
   - Federation-level meta-neurons (Level 3)
   - Cross-cluster influence learning
   - Spike-based distributed consensus
   - Emergent collective behavior detection

2. Temporal Hypergraphs (temporal-hypergraphs.md)
   - Time-varying hyperedges with validity intervals
   - Causal constraints using spike-timing inference
   - Extended Cypher with temporal operators
   - Temporal MinCut for vulnerability detection
   - Causal MinCut for intervention planning

Both designs integrate deeply with existing SNN architecture and
subpolynomial-time MinCut algorithms.

Co-authored-by: Claude <noreply@anthropic.com>

Author: ruvnet