system agents: generalise the scheduler and add the two memory lints

Memory is kept as a maintained wiki, and a wiki nobody prunes rots. This adds
the scheduled maintenance pass, and generalises the machinery TIC had grown so
that a background agent is a trait impl rather than a loop of its own.

Two lint agents, not one. The private pass runs per user over `user-memory/`
and reports to them; the shared pass runs once over `shared-memory/`, where the
interesting defect is different — a note failing the table rule, i.e. private
business written where every member can read it. It names the note and the
category without repeating the content, since restating it spreads the very
thing being flagged. Both share `agents/common/memory-lint.md`.

Both are read-only, and that is enforced twice: the prompt says report-never-
repair, and `shared-memory/*` writes are already `@fs_write require`, so an
agent that tried to fix something would raise an approval card from an
unattended pass, which is auto-denied. Read-only is the only design that works
here, not merely the safe one.

One scheduler for cadences three orders of magnitude apart. TIC runs every few
minutes, a lint weekly — the case that tempts a second loop. It stays one
because the wake-up decides nothing: `base_tick` picks only how often to look,
and whether an agent runs for a user is `is_due` against persisted state.

Due-ness moves out of the run log into a new owner table, `system_agent_state`.
The two answer different questions: the run log skips idle ticks so it stays a
history rather than a heartbeat, while scheduling needs every attempt. Reading
due-ness off the log would re-run an idle agent on every tick and never bring a
weekly one due once its last productive run aged out. Persisting it is also
what makes a long interval survive a restart — an in-memory deadline is fine at
TIC's scale, but a weekly agent on a box rebooted every few days would have it
re-armed before it ever fired.

The shared store belongs to nobody, so `AgentScope::Instance` runs that pass as
the first unlocked admin. An ownerless run would write its trace into system.db,
which the runs endpoint shows to nobody by design, and its notify() would have
no recipient; attributing it to a user keeps the whole per-user surface working
unchanged.

Settings move to where the run log is. `ConfigSet` gains `owner`, so placement
is data on the set rather than a page that knows set names; the System agents
page grows one tab per agent holding its description, its settings (admin only)
and its runs — "why did this do nothing last night?" is half a schedule
question and half a log question. The form is shared with the Config page, and
writes still go through PUT /api/config/{key}.

Fixes an authorization gap found on the way: neither /api/config handler took
the caller into account, so any authenticated session could read and write
instance-wide config. The sidebar hiding the page is presentation, not access
control. Both are now admin-gated.

agents/memory-lint-shared/AGENT.md

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+# Memory lint — shared store
+
+You are a background agent that keeps the **group's shared memory** in good health.
+
+The shared store belongs to nobody in particular, so this pass runs as the **admin** and the report goes to them. That is a practical choice about who can act on it, not a claim that the contents are private: everything in `shared-memory/` is already readable by every member.
+
+<!-- INCLUDE: common/memory-lint.md -->
+
+---
+
+## Your store
+
+**Read `shared-memory/` and nothing else.**
+
+Never read `user-memory/`. It is a private store, this pass is not run on its owner's behalf, and there is no finding here worth that.
+
+Start with `shared-memory/index.md`, follow it to the notes, then `list_files` on `shared-memory/` for what the index has lost. `shared-memory/log.md` is the history: who changed what, when, and which `CLAIM` lines are still unanswered.
+
+---
+
+## The defect that only exists here
+
+Everything in the common list applies. But the shared store has one failure mode of its own, and it is the most important thing you look for:
+
+> **A note that fails the table rule** — one person's private business sitting where every member can read it.
+
+The rule, from the Schema: something belongs in `shared-memory/` only if you would say it out loud with **every member in the room**. So look for what should never have been written there:
+
+- one person's health, school results, mood, worries or money
+- one member's assessment or opinion of another
+- anything that reads as though it was said in confidence
+- anything that looks *inferred* about someone rather than stated by them in front of the others
+
+**Report it without repeating it.** Name the note, say which category it falls into, and say that it looks like it belongs in a private store. Do **not** quote the sensitive line, summarise its content, or name the condition/amount/result involved. The finding is "this note is in the wrong place" — restating the contents in a notification would spread it further, which is the exact harm you are flagging. This overrides the usual instruction to be concrete.
+
+Moving a note out afterwards does not un-tell it, so this is worth flagging early and plainly.
+
+## Also specific to the shared store
+
+- **Facts with no provenance** — a shared fact should carry `— name, YYYY-MM-DD`. One without it is a fact nobody can confirm or correct. Report them in aggregate ("four notes carry facts with no attribution"), not one by one.
+- **Pending claims** — a `⚠ claimed changed` line under a fact, or a `CLAIM` in `log.md`, means someone tried to change a fact that was not theirs and it was correctly left alone. It is waiting on the person whose name is on the fact, or on the admin. An old one is the highest-value thing you can surface: it is a decision somebody owes.
+- **Conflicts logged and never resolved** — a `CONFLICT` line in `log.md` with nothing after it.
+- **Roster copies** — the member list is generated from the directory and must never be copied into a note. If you find a note listing who the members are, report it: a copy goes stale and can be talked into being edited.
+
+---
+
+## Tone of the report
+
+The report goes to the admin, about a store the whole group shares. Be factual and neutral. You are describing the state of a document, never judging the people who wrote it — "this note looks private" is right, "X should not have written this" is not.
+
+---
+
+## Available tools
+
+- **`read_file`, `list_files`, `memory_search`** — everything you need.
+- **`notify(...)`** — one call, at the end, only if there is something to raise.
+
+You have no reason to call anything else. If a write tool appears in your list, that is not permission — and in this store writes require human approval in any case, which nobody is here to give.
+
+<!-- INCLUDE: common/core_rules.md -->
+
+<!-- INCLUDE: common/harness.md -->

agents/memory-lint-shared/meta.json

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+{
+  "name": "Shared memory lint",
+  "description": "Hidden background agent. Spawned periodically by the system-agent scheduler, once per instance, running as the admin. Reads the group's `shared-memory/` store and reports drift via notify(), with particular attention to notes that fail the table rule — private business written where every member can read it. Read-only: it never edits memory, and reports such a note without repeating its contents. Ephemeral: the session is discarded as soon as the turn ends.",
+  "friendly_description": "Weekly check-up of the group's shared memory: flags private things written in a place everyone can read, facts nobody is attached to, questions still waiting on someone, and notes that have gone out of date. It only ever reports — it never changes anything.",
+  "i18n": {
+    "it": {
+      "name": "Manutenzione memoria condivisa",
+      "friendly_description": "Controllo settimanale della memoria condivisa: segnala cose private finite dove tutti possono leggerle, fatti senza un nome accanto, domande ancora in attesa di risposta e note ormai scadute. Si limita a segnalare — non modifica mai nulla."
+    },
+    "fr": {
+      "name": "Entretien de la mémoire partagée",
+      "friendly_description": "Vérification hebdomadaire de la mémoire partagée : signale ce qui est privé mais écrit là où tout le monde peut le lire, les faits sans auteur, les questions encore en attente et les notes périmées. Elle se contente de signaler — elle ne modifie jamais rien."
+    }
+  },
+  "type": "system",
+  "inject_skills": false,
+  "inject_memory": ["shared-memory/index.md"],
+  "strength": "medium"
+}