v1.10.0: DaggerAgent 1.10.0

DaggerAgent 1.10.0

Manage the Banter connection from the web UI: a Bant tab in service
mode (dagger serve) holds the room connection in-process, so no
second dagger banter process is needed.

• Status card: connection state, identity, rooms, key fingerprint and
  last error, with Connect / Disconnect buttons.
• Enrolment box: paste a one-time code from the Banter client's agents
  page; the machine makes its own key (DPAPI-protected on Windows),
  the enrolled nick and fingerprint come back, and the config is
  updated to match - the leftover password is cleared, so Connect
  just works. An existing key is never overwritten.
• Config section persisted to runtime-config.json: server, user,
  rooms, key path, password (legacy), LLM endpoint + model for room
  turns, routing attributes, system prompt, and auto-connect on
  service start (Banter:AutoConnect).
• Scriptable at /agent/banter: GET, POST /config, /enrol, /connect,
  /disconnect. The password never leaves the server (hasPassword
  only); the key surfaces only as its path and public fingerprint.
• New Banter:EndpointId pins room turns to a configured LLM endpoint
  instead of the active default.
• Fix: an empty ConversationState.Model now means "the endpoint's
  default decides" instead of overriding it with an empty model id,
  which the OpenAI serializer rejects ("Empty encoded value").

Verified in a real browser against a live Banter server: enrol from
the tab, key login (signed nonce), and a room mention answered through
a configured LM Studio endpoint.