fix(tmux): stop nested prefix keys and TUI Alt+digits from moving other clients

Docker and owned-remote tmux servers kept the stock prefix table, so Ctrl+Q
then )/(/s/w/L switch-client'd the inner client onto a sibling. Those create
chains now leave only C-q send-prefix.

codeman tui bound M-1..M-9 in the server-wide root table. The keys stay, but
switch-client runs only for the attaching client (tty plus a one-shot pid).
A browser tab's Esc-then-digit no longer jumps sessions, and a killed TUI
leaves a binding that matches no live client.

Co-authored-by: DDT <1786035110@qq.com>

docs/tui.md

@@ -193,7 +193,9 @@ wears a bar across the top:
 
 That is the **session strip**: the other sessions stay visible from inside a pane,
 numbered exactly as the dashboard numbers them, with the one you are in inverted.
-`Alt+1`..`Alt+9` switch between them without going back to the dashboard first. With
+`Alt+1`..`Alt+9` switch between them without going back to the dashboard first. Those keys
+run `switch-client` only for this terminal's tmux client, so a browser tab on the
+same socket cannot use them to jump sessions, Esc followed by a digit included. With
 more sessions than fit, the strip shows a window around the current one and marks
 each cut end with `…`; the way-out hint is measured first and always keeps its space.