tmux: shrink status-right-length from 451 to 60

status-right-length was 451 on a 158-column terminal. tmux lays out the
left segment, then the window list, then gives what is left to the right
segment -- and with the right declared three times wider than the screen
there is no stable allocation. Anything that changes the window list's
rendered width pushes the right segment off entirely, which is why the IP
and clock kept vanishing while the left side stayed put.

The window formats render to 92 characters because of the nested
conditionals that pick a circled number per index, so the list is wide
enough to matter.

This is what the "seizure" was. Not X, not NVIDIA, not picom, not hotplug
events, not the monitors, not mosh, not tmux's version, and not the shell
substitution in status-right -- it reproduced on a bare framebuffer console
with none of those present, and it was intermittent because it depended on
what the window list happened to render at that moment.

.tmux.conf

@@ -73,7 +73,7 @@ set-window-option -g mouse off
 
 # color scheme (styled as vim-powerline)
 set -g status-left-length 52
-set -g status-right-length 451
+set -g status-right-length 60
 set -g status-style fg=white,bg=colour234
 set -g pane-border-style fg=colour245
 set -g pane-active-border-style fg=colour39