v0.3.0

• Added: a list of connectors takes owner, as a list of connections
  does, and sends it in its connector.list question, so your
  authorizer can let a service list one person's servers, for instance
  to remove a closed account's, with a filter naming that person alone.
  A list that names no owner asks as before.

• Added: one reason of a deny of connection.use reaches the caller.
  When your authorizer denies a use with kept_apart_from_google, for
  a session that already used a connection you keep apart from this one,
  Pons answers 409 connection_not_connected with that reason in
  details.reason, at the MCP and the forwarding address, so the
  session can tell the person to start a new conversation. Every other
  deny of a use is still 404 connection_not_found. Send this reason
  only for a connection the session holds.

• Added: MCP servers added by their address for others. The owner of an
  added connector is the one your authorizer's allow of
  connector.create names, a string Pons gives no meaning: use one for
  a person, one for an organization and one for the whole installation.
  A list of connectors shows the added connectors of every owner the
  allow's filter names, and a connect to another owner's connector asks
  connector.read of it first, so an organization's members connect
  the servers its administrators added when you let them read those
  connectors. Under the owner policy an added connector stays its
  owner's alone.

• Added: for your authorizer, the action connector.update, asked by an
  edit with the connector's id and owner, and by a list once for each
  owner on its page with that owner and no id, to show how many
  connections use each of that owner's connectors. connection.create
  of a connect to an added connector sends connector_owner. The allow
  of connector.create may carry the limit vouched: true, which says
  someone you trust looked at the server; send it for an administrator's
  add alone. Roll your authorizer before this Pons: one built on
  latere.ai/x/pkg/authz/server that does not know connector.update
  answers it 400, and an edit fails closed with 503 authorizer_unavailable. Do not send vouched to a Pons before this
  one: it does not know the key, and every add fails closed with 503.

• Added: PATCH /connectors/{id} changes an added connector in place,
  holding from the next request on every replica with no restart: its
  title, description, icon, tool marks, auth.scopes, a
  vouched-for connector's auth.client.secret, and disabled. Its
  name, kind, url, auth.type and client id are
  400 immutable_field. A connector turned off stays listed; a connect
  to it is 409 connector_disabled, a call through a connection to it
  is 409 connection_not_connected with details.reason
connector_disabled, and its connections and their credentials are
  kept until it is turned on. A removal is still 409 connector_in_use
  while a connection uses it.

• Added: an add needs only the address. auth is optional on
  POST /connectors: Pons asks the server with no credential, after
  the authorizer's question and within PONS_CREATES_PER_MINUTE, and
  stores none, oauth or token from its answer, with the hint "API
  key" for a server that takes a key. An auth the answer does not
  admit is 422 auth_mismatch, and a server that does not answer as one
  that can be connected is 422 server_unreachable, with the status or
  the failure and never the address. Every add now makes these
  requests, so an address whose server does not answer can no longer be
  added.

• Added: a server added by its address signs people in. Pons identifies
  itself by a vouched-for connector's own client, auth.client with its
  id and secret, sealed and never answered; else by the connector's
  client metadata document; else by registering at the server, which the
  installation keeps per issuer and reuses for a second connector there.
  A server whose authorization server does not say it sends iss signs
  in at /v1/callback/{key}, its issuer's own redirect address, which
  refuses an answer meant for another server. An added connector's view
  says auth.client (own, document or registered), disabled,
  vouched, and, for its own client, auth.redirect_uri, the address to
  register that client with.

• Added: GET /connections/{id}/tools, the tools a connection's server
  lists through it, with the effect the connector's marks give each and
  whether they hide it, asked each time and recorded as no call. And
  connections on an added connector's view, to a caller your
  authorizer lets change it: how many connections of every owner use
  it.

• Added: PONS_MAX_ADDED_CONNECTORS, 50 by default: how many connectors
  one owner may add. One more is 409 connector_limit, and other
  owners' adds go on.

• Changed: the store's schema moves to version 2, which adds columns to
  connectors. It runs at start as every migration does; a binary
  before this one refuses a schema at version 2.