Three new REPL commands:
- /sync all — syncs all enabled connectors at once with status per connector
- /improve — RLHF-style interactive session to validate/correct entities and
  relationships; changes saved to graph + preferences.json immediately
- /visualize — interactive graph explorer using Rich trees/tables; browse by
  type, explore relationship trees, search by name, navigate between entities

Background 10-minute auto-cycle: REPL starts a daemon thread on startup that
runs sync→extract→context every 10 minutes when the background daemon is not
already running (daemon handles the same pipeline via its agents when running).

No new dependencies — both new commands use only Rich (already required) and
stdlib sqlite3/input().

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>