v5.0.0 — mark a page by moving things and striking things out

Breaking

• Stop is withdrawn. Asking the agent to stop a round mid-flight could not
  do the one thing it promised — interrupt the turn — so it is out rather than
  half-working. The cancelled command, /api/cancel, the cancel sentinel
  and the CANCELLED stream event are gone, and check always exits 0. A
  round already on disk with status cancelled stays terminal, so nothing in
  your project needs migrating. What it would have to do to come back is written
  down in docs/review-wishlist.md.
• Host profiles move to plugins/vstack/host-profiles/. hosts/ now holds
  only the adapter markdown that maps review operations to a product's tools.
  This is inside the plugin, so an installed copy updates itself.

Added and fixed

• Linked now means a session is listening. The workspace used to show Linked
  on evidence a session could produce without receiving anything. A stream
  watcher now opens with a HANDSHAKE line naming a command, and its heartbeat
  only starts once ack answers it; unanswered, the watcher exits after two
  minutes (--handshake-timeout <seconds>). Presence also requires rounds to
  move: one queued and unclaimed for 90 seconds drops the link, because a
  watcher whose events nobody reads should look the same to you as no watcher at
  all. A watcher covering no review reports UNLINKED rather than LINKED.
• The cog says which version you are on. It shows the version the workspace
  loaded with and the one the server is running now, and offers a reload when
  they differ — so a tab left open across an update says so.
• An answer written on a comment carried in from an earlier version is kept.
  Replies and note edits copy the comment into the current version first, so the
  answer lands in the file the workspace reads back.
• Two new ways to mark up a page: Move and Delete. A toolbar beside the page
  holds Comment, Move and Delete — what Annotate draws with, on keys c, m
  and d. Neither new tool needs a note: the mark is the instruction, and
  anything you type adds to it. Both outline whatever the pointer is over, so
  the element the gesture will take is settled before you press.
  • Move draws an arrow from a thing to where it should go. It records the
    element you dropped it on and which side of it — inside, before, or after —
    so your agent is told "after the Cancel button" rather than "180px right",
    which stops meaning anything the moment the page reflows.
  • Delete strikes out what should go. Drag across text and exactly those
    words are marked for removal; the strike finds them again by their text when
    the page is rebuilt, so it stays on them. Click an element instead and the
    whole thing is marked.
• A watcher finds a review whose page lives outside the directory it was
  started from. A review's files sit beside the page under review, and
  watch --all found them by walking the directory it ran in. A page written to
  a temp directory took its files with it, so the watcher walked straight past a
  running review and the workspace said Unlinked while a session was in fact
  listening. Serving now leaves a pointer where it was run from, and the watcher
  follows it.
• A watcher that covers no review says so. It reports UNLINKED instead of
  LINKED, because nothing is listening to any workspace at that point whatever
  the handshake proved. A handshake also carries the token it printed, so one
  watcher's answer no longer brings a different watcher live.