Operator guide: privacy, retention, and scrub for Postgres + Chroma + rooms + mail

[rosspeili]

Problem

Mission and README emphasize memory and mail; there is no single place describing what is stored where, how long, and how to wipe or export safely (kun.py sensitivity is noted in SECURITY.md only at high level).

Goal

New docs/PRIVACY_AND_DATA.md (or section in MEMORY_AND_RAG.md): conversations, embeddings, room CSVs under outputs/rooms/, mail credentials in env, /forget semantics—plus a short “before you share this machine” checklist.

Acceptance criteria

• Linked from README documentation map and/or SECURITY.md.
• No new promises that contradict current code behavior.