memory: reshape the two stores into a maintained wiki

Memory was a scrapbook: notes accumulated, nothing kept them consistent,
and shared memory had no rule saying what belonged in it. This adopts the
LLM-wiki pattern — the assistant maintains an evolving artifact rather
than re-deriving knowledge each session.

The schema (agents/common/memory-wiki.md, included by the three type:chat
agents) adds an append-only log.md beside each index.md, names Ingest /
Recall / Lint as habits, and states the rule for shared memory: write it
there only if you would say it out loud with every member in the room.
One person's health, results or another member's opinion of them stays
private — that is what shared folders, not shared memory, are for.

Tampering is the reason the rules are shaped this way. Shared facts carry
provenance and are superseded rather than erased, and a member who
contradicts a fact they did not write gets a logged CLAIM instead of an
overwrite: only the originator or an admin can turn it into a change.
The approval gate cannot enforce this — it asks the caller, who is the
same person pushing — so a per-role write permission on shared memory is
still the real boundary. The prompt is the etiquette, not the fence.

append_file is a new fs tool because the log needs a write that cannot
shorten a file. On memory paths it is one SQL statement, so concurrent
appends (parallel tool batches, two sessions of one user) cannot lose a
line — a dropped line in an audit trail is worse than a failed write. It
is auto-allowed on shared-memory/log.md at a lower priority than the
shared write rule: gating the trail would be friction with no safety, and
a rejected log write yields an unlogged change.

memory::scaffold seeds index.md / log.md / user.md so the schema does not
describe files that do not exist. Seeded empty rather than left absent:
a missing note resolves to nothing at injection, so the model cannot tell
"nothing recorded yet" from "this mechanism is not running".

__MEMBERS__ renders the roster from users + roles instead of a note the
model maintains. A remembered copy drifts and can be talked into being
edited; this one bypasses the model entirely. users.notes are excluded —
they are the admin's private notes about a person and this block is
visible to every member.

Still open: a UI to browse memory (list_dir does not classify memory
paths yet), a tool-written revisions table (log lines are still typed by
the model), and the periodic lint pass.

agents/assistant/AGENT.md

@@ -12,6 +12,12 @@ Read this before you reply and adapt to it — their name, their language, and a
 
 If the name or language shows as `unknown`, pick it up naturally as you talk and save it to memory — never re-ask something you already learned.
 
+## The other people here
+
+Everyone who shares this instance. This list is read from the directory, so it is always current — do not keep a copy of it in memory, and do not try to correct it here (an admin edits it in the Users page). How people are *related* to each other is not in it: that belongs in shared memory.
+
+<!-- MEMBERS -->
+
 ## Your workspace
 
 The `data/` directory (inside your home) is your own scratch space — write there freely: generated files, notes, one-shot scripts, downloads. **Default to `data/` for everything you produce.** When a path is relative, prefix it with `data/`; a bare filename lands somewhere less tidy. Persistent **memory** is separate (see below) — durable facts go to `user-memory/`, never under `data/`.
@@ -22,6 +28,8 @@ Your home (`~`) and the shared folders are real directories: read and write them
 
 <!-- INCLUDE: common/memory.md -->
 
+<!-- INCLUDE: common/memory-wiki.md -->
+
 ## Your `user.md` — the essentials always in front of you
 
 `user-memory/user.md` is your **single most important note**: the handful of facts about this user you never want to be without — who they are, how they like to be helped, what is going on in their life right now. It is injected into every conversation automatically (alongside the two indexes), so keep it **curated and current**.