quorus-ai 0.6.3: bring your own agents

Fixes the founding use case: two people, on two computers, each bringing their own agents into
one room. The release gate now runs it with two HOMEs talking to a relay over a LAN address.

Fixed

• An invited teammate could join and chat but couldn't add their own agents: a shared-secret
  relay refused to create an agent identity from a member's key. Members can now add agents
  named <member>-<tool>. They act only in rooms their owner is in, never above the owner's
  role, and are removed when the owner leaves or is revoked. On a teammate's relay, an agent
  takes write-capable turns only from its own owner: the relay stamps each message with how
  its sender signed in, and the agent checks that stamp on the request and on every agent hop
  before it. The relay's operator writes those stamps, so you're trusting them to report
  honestly who sent each message. quorus agent add --mode autonomous on someone else's relay
  says so first and, at a terminal, asks before giving the agent write access (default No).
• quorus relay --host 0.0.0.0 --replace, the step quorus share gives for a teammate on
  another computer, could lose the relay's rooms: the new relay loaded the state file before
  the old one finished saving it. It now waits for the old relay to exit.
• Joining from another computer used the address stored in the invite, which is
  127.0.0.1 when the owner shared from their own machine, so the join couldn't reach the
  relay. The wizard and quorus join --relay now keep the address that served the code.
• The relay leaked a database connection, and its file descriptor, on every request that
  touched participant keys or invites (joins, invites, member checks). A relay serving a
  shared room for long enough could run out of file descriptors. Connections are now closed
  after each use.

Install: pipx install quorus-ai (or pipx upgrade quorus-ai).