hive: versioned central config with layered targeting ...

The hive now stores one config document for the fleet: a list of layers,
each with an optional match (names/instance_ids/tags), appended as immutable
versions. Publish, history, rollback and status are admin-only (admin key or
loopback); the swarm key reads config, so a compromised instance cannot
rewrite what the fleet runs.

Delivery has three paths that degrade into each other: a push notification,
a 'you are behind' hint in the announce reply, and a periodic sweep over
instances that still report an older hash. Acks are tracked per instance and
version, so the status view answers who took the config and who needs a nudge.

A layer list is validated as a whole; an empty list is a legal document that
means 'no overlay'.

swarm stage 2: peer-to-peer channel — /peer endpoints + peer tool ...

Server side (navi/api/routes/peer.py, port 8099):
- GET /peer/hello — open discovery ping (name, uuid prefix, version)
- GET /peer/status — PSK; identity, uptime, machine facts, hive view
- POST /peer/ask — PSK; one-shot agent run under PEER_ASK_PROFILE
  (default server_admin) answers, one concurrent ask at a time
- loop guard: answering agent runs without the peer tool (deterministic
  recursion cut) + own-uuid asks refused with 409
- verify_swarm_key in navi/swarm.py accepts .swarm-key.previous
  (rotation window, constant-time)

Client side (navi/tools/peer.py):
- peer tool: list (hive book, stale cache fallback marked), status,
  ask by swarm name; asks go direct peer-to-peer, hive never on the
  message path
- audit events on both sides (peer.ask_sent/received/answered/failed)

peer tool added to server_admin, navi_code, developer profiles.

swarm stage 1: instance identity, PSK, hive registry, announce loop ...

- navi/identity.py: adjective-animal names + uuid in instance.json
  (generated at install, renameable by hand)
- navi/swarm.py: HiveAnnouncer - periodic POST /announce to the hive
  with non-blocking reachability tracking (transitional logs, /health
  export, hive_status context provider reports outages to the agent)
- hive/: standalone FastAPI address book (SQLite, port 8087, PSK via
  X-Swarm-Key with .swarm-key.previous rotation window, TTL online
  status, host from client IP, port from payload). Not installed or
  started by default - run manually on the main server.
- ports moved to 8099 (API) / 8098 (UI MCP)
- install.sh: PYTHONIOENCODING=utf-8 in the systemd unit, generates
  instance.json and .swarm-key on fresh installs