Add a memories table (survives index rebuilds) for agent-written
conclusions with provenance (session, message range, project). The agent
writes markdown files via Write tool (user-approved), then registers
them via a --remember CodeAct script with remember(). Recall via
memories() in --query scripts, filtered by project/session/time.
Separates query (read-only, assertReadOnlySql) from remember (write)
execution contexts in runtime.mjs.