Serbero v0.2.0

Groundwork for assisted mediation. Mediation stays off, and notification
works as in v0.1.0; the startup log also shows Serbero's npub.

Added

• Mostro chat transport: sessions and messages tables, dispute chat keys,
  taking a dispute (admin-take-dispute) on nodes that speak protocol v2,
  exchanging validated chat messages with both parties, stopping on human
  takeover, and resuming live sessions after a restart.
• A staging run against a real mostrod through Ortsom.
• A provider-neutral judge contract, a recorded judge for tests, and the
  TypeSafe adapter for Jev.
• The judge state built from a session, with Nostr identifiers redacted.
• Party message catalogs in English, Spanish and Portuguese, with rule tests
  for every catalog.
• A Spanish judge spike (eval/spike/) and the qs-1 turn question set it
  informed.
• The startup log shows Serbero's npub, the form a Mostro admin uses to
  register it as a solver.
• A README that explains mediation end to end: what the parties and solvers
  see, the guarantees, languages, and how to enable it.
• Optional [[observers]]: services such as mostro-watchdog get one line
  per mediation update (mediating, could not start, handed off, guidance
  sent), once per dispute, without any party text. Notices are queued with
  the state they report and delivered by their own task, with retries.
• Dockerfile, deploy/compose.yml, and a hardened systemd unit
  (deploy/serbero.service), with README sections on running them and on
  backing up the database. CI builds the image and smoke-tests it.
• Each release publishes a multi-arch container image (amd64, arm64) to
  ghcr.io/mostrop2p/serbero with build provenance. deploy/compose.yml
  runs a pinned published version; deploy/compose.build.yml builds from a
  checkout instead.
• cargo release minor -x on main cuts a release in one step: it bumps the
  version, dates the changelog, publishes the crate to crates.io
  (cargo install serbero), and pushes the vX.Y.Z tag that publishes the
  binaries and the container image.

Changed

• The evaluation binary is now serbero-eval
  (cargo run --bin serbero-eval), so cargo install serbero does not
  install a command named eval.
• Logs are colored only on a terminal and never when NO_COLOR is set, so
  docker logs and the systemd journal carry no escape codes.
• Solver DMs carry the dispute id in the message id, and every solver
  message starts with Dispute <dispute_id> · <subject>, so clients such as
  Mostrix can link and classify them without parsing prose
  (docs/messages.md §3). The new-dispute, reminder, taken, mediation and
  final-report texts moved to that header.