docs: complete README rewrite — theory-first, architecture, results

Restructured to emphasize the theoretical contribution:
- Core contribution section with benchmark results upfront
- Theoretical framework: V(m,t,c), Lyapunov stability, adaptive cooldown,
  spreading activation, information preservation bounds
- Full system architecture diagram
- 3-layer retrieval pipeline visualization
- Memory Pipeline API with code examples
- Ablation study table with per-component contribution
- Complete controller matrix (15 controllers)
- Directory structure map

Design: theory → architecture → implementation → results flow

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: QUSETIONS