docs: document activation lifecycle updates

feat: finish activation-based memory lifecycle rollout

fix: require condensed summary to write session note — leaf-only stubs render empty

fix: skip empty session stubs in vault sync — only write session notes when summaries exist

Update README with memory quality, harvest, vault, export/import, and hardening docs

Fix recall type diversity, memory_correct dedup bypass, and entity cleanup

Harden infrastructure: WAL mode, harvest security, vector refresh, rate limiting, DB optimization, config validation, export/import, health check

Add periodic memory harvest — automatic background extraction every N turns

Harden engram: entity extraction, capture quality, dedup, error handling, tests

Fix entity extraction across all paths and add type-based search ranking

Fix vault-mirror, entity quality, MEMORY.md sync, and add automated vault-sync

Tighten structural entity extraction quality

Harden entity extraction against junk aliases

Fix SDK compatibility and tighten recall safeguards

Harden Engram rollout and entity world model