v0.2.0

Kubernetes high-availability, a reworked dashboard, and a full QA sweep. A
second QA pass over the real prospero/caliband stack filed 23 findings; all
are fixed here, alongside first-class leader election for the k8s fleet backend
and a new agent-timeline dashboard.

Added

• Leader election + attach lifecycle for the K8sFleet backend. The
  session-plane attach — the one path that writes an agent's events to the shared
  store/bus — is now gated on a per-agent ownership lease, so with 2+ prosperod
  replicas exactly one replica owns, attaches to, and emits each agent (no more
  duplicate SSE events or racing per-stream seq allocation). Standalone is
  unchanged (SelfOwnsAll); a clustered deploy builds a LeasedOwnership lease
  plus heartbeat. Attach tasks are now promptly torn down on stop/remove/restart,
  and any agent observed Running — including operator- or peer-created ones —
  is streamed by the lease owner
  (#108,
  #112,
  #113)
  (#138).
• Dashboard agent timeline, tool-call inspector, and run header — a folded
  event timeline with expandable tool-call segments and a per-run turns/outcome
  header (#5)
  (#96).
• prospero-types crate — the normalized FleetEvent/model DTOs extracted
  into a small, wasm-compatible serde-only crate the WASM dashboard can share
  (#98)
  (#100).

Changed

• Under PROSPERO_FLEET=k8s, prosperod no longer builds a local
  FleetManager/poll loop; the k8s backend serves directly over the shared
  store/bus (#83)
  (#92).
• /readyz now reports workspaces_total/workspaces_healthy/
  workspaces_unreachable (was repos_*), and user-facing error wording says
  "workspace" not "repo", matching the vocabulary used everywhere else
  (#116,
  #117)
  (#135).

Fixed

• Dashboard. Terminal-agent SSE streams no longer reconnect-storm into an
  unbounded, duplicated timeline with runaway memory
  (#105)
  (#128); tool calls resolve
  ok/fail instead of showing "running" forever (paired by tool_use_id)
  (#106)
  (#131); the fleet summary
  shows the workspace count, the misleading $0.0000 cost is gone, and a favicon
  is served (#115,
  #109,
  #119)
  (#134).
• API. Duplicate workspace registration returns 409 Conflict, not a
  misleading 503 (#111)
  (#139); an unknown agent's
  events endpoint returns 404 instead of 200 []
  (#118)
  (#135); api_key_from_env
  on a keyless provider is rejected at config-set time, and rm no longer races
  a just-spawned agent or lags the fleet view
  (#120,
  #122,
  #123)
  (#137).
• k8s hardening. The session-plane bearer token is never sent over plaintext
  (#107)
  (#133); unrecognized
  CalibanTask phases map to a terminal state, calibandEndpoint is validated,
  lock poisoning can't wedge the fleet view, the token compare is constant-time,
  and --fleet-backend k8s on a non-k8s build fails before any side effects
  (#114,
  #121,
  #125,
  #126,
  #127)
  (#136).
• Tests. De-flaked the distributed_bus PG suite under parallel shared-DB
  load (#110)
  (#129) and
  cli_drives_the_full_stack (#85)
  (#94).