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>

test/docker-exec-options.test.ts

@@ -106,6 +106,12 @@ describe('buildDockerLaunchCommand', () => {
     expect(cmd).toContain('tmux -L codeman-docker setenv -g CODEMAN_SESSION_ID');
     expect(cmd).toContain('new-session -A -s codeman-dkr-1a2b3c4d');
     expect(cmd).toContain("sh -lc '");
+    // The in-container tmux keeps prefix C-q. Without this reduction its stock
+    // prefix table runs switch-client / choose-tree for the inner client.
+    const unbind = cmd.indexOf('unbind-key -a -T prefix');
+    const bind = cmd.indexOf('bind-key -T prefix C-q send-prefix');
+    expect(unbind).toBeGreaterThan(cmd.indexOf('prefix C-q'));
+    expect(bind).toBeGreaterThan(unbind);
   });
 
   it('pins a deterministic conversation id with a reboot-surviving fallback (fresh launch)', () => {