`tty7 exec %N -- CMD` types a line at an existing pane's shell prompt,
follows the shell integration's OSC 133 marks to the command's end, prints
what it printed (rendered to text by default, `--raw` for the bytes) and
exits with its exit code. `--timeout` exits 124 and leaves the command
running. A pane with no prompt marks, or one not at a prompt, is refused
before anything is typed.
`tty7 send` can take its text from `--stdin` or `--from-file`, sent byte
for byte and never echoed in --json, so a secret stays out of `ps` and
shell history. `--paste` frames the text the way the GUI's paste does:
bracketed when the pane has mode 2004 on, unframed otherwise, reported in
--json. The framing moves into tty7-core (`core::paste`) so the GUI's
clipboard paste, the agent prompt and the CLI share one construction, and
the daemon now reports each pane's bracketed-paste mode in PaneContext.
Closes#839Closes#838
