docs: add Mermaid diagrams, metrics page, and document new features Replace all ASCII art diagrams with Mermaid.js across 7 pages. Add Metrics & Observability page for pkg/metrics package. Document intent classification, research phase, chunked planning, coverage gates, and ship preflight in Six-Phase-Workflow. Fix Edit tool risk level (medium → dangerous), update Grep with ring buffer streaming and ReDoS protection, add O(1) dedup notes to Code-Intelligence and Prompt-History pages.

eshanized committed Jun 21, 2026