saikai 0.6.1 — a pane that keeps its own promises

A cross-terminal audit of the pane's own contract: what it tells a child it is, and
what it actually does. Every item is a place the two disagreed, so the symptom only
appeared on some hosts or under some children.

Fixed

• A multi-line paste could be submitted line by line. A PTY read that ended on a
  CSI intermediate byte (the $ of \x1b[?2004$p) was released instead of held, so
  saikai's DECRQM scanners matched neither half and the query went unanswered — a child
  that sets bracketed paste and then verifies it concluded the mode was unsupported.
  pyte's own parser spans the split, which is why nothing looked broken.
• DECRQM no longer claims modes saikai does not implement. The position-accurate
  overlay recorded every private mode a chunk carried, so a set-then-verify in one
  write was told "1 = set" for a mode nothing here honours, while the same query one
  read later correctly got "0 = not recognised".
• The alt screen is detected in a combined DECSET. A child that writes its whole
  entry at once (\x1b[?1049;1002;1006h) produced no boundary, so pyte's single buffer
  kept the pre-alt frame under the child's new UI. AltScreenTracker had a second copy
  of the same pattern; it now shares one.
• Arrow keys follow the child's DECCKM state. The pane always sent CSI while the
  mirror replays ?1h into xterm.js, so the same arrow reached the child as \x1bOA
  from a browser and \x1b[A from the pane.
• A dropped image is reported. The pane answers DA1 byte-identically to Windows
  Terminal — which advertises sixel — and then drops every DCS, so a graphics payload
  vanished silently. It now says so once per pane.
• Terminal remote-control sockets no longer reach a pane child. kitty and alacritty
  were scrubbed by their identity variables while KITTY_LISTEN_ON and
  ALACRITTY_SOCKET went through, which let a child drive the real outer window
  (kitten @, alacritty msg); KONSOLE_DBUS_* was the same over D-Bus. Whole
  families are stripped now, as WezTerm's already was.
• The list's viewport no longer flicks to the cursor row under load. The
  cursor-scroll suppression closes on a queued callback, so a rebuild that starts
  before the previous one's callbacks drain opens a second window — and a boolean let
  the first window's end re-arm the second's pending scroll. It counts now.

Install or upgrade: uv tool install saikai / pipx upgrade saikai.
Full changelog: https://github.com/m-morino/saikai/blob/master/CHANGELOG.md