Streamed responses no longer insert real newlines at terminal width —
logical lines are emitted whole and the terminal soft-wraps them, so
highlight-copy rejoins the full line (emulators only keep linebreaks
the app actually printed). This is the CLI equivalent of the TUI's
selection copy, which reads logical source lines from its screen
buffer. TTFT perception is preserved by mirroring the unfinished
line's tail into the spinner status text instead of chunk-printing.
/copy now prefers OSC 52 when running over SSH (SSH_CONNECTION /
SSH_TTY / SSH_CLIENT) — native tools there write the REMOTE clipboard,
which is never what the user wants. The CLI's OSC 52 writer also gains
tmux/screen DCS passthrough wrapping, mirroring the TUI's
wrapForMultiplexer. Fixes#31528 for the CLI surface.
Sabotage-verified: restoring the old chunk emitter fails 3 of the new
tests (hard-wrap detection, spinner mirror, unbreakable-run split).
