Splitting panes from command line causes a crash.

### Windows Terminal version

1.23.12811.0

### Windows build number

10.0.26100.6508

### Other Software

_No response_

### Steps to reproduce

Launching the following from command prompt:

wt.exe -M -p Arch_Clear ; split-pane -V -s .55 -p Arch_Clear ; split-pane -H -s .15 -p Arch_Clear_Small ; split-pane -v -s .25 -p Arch_Retro ; mf up ; split-pane -V -s .3 -p Arch_Clear_Small ; split-pane -H -s .5 -p Arch_Clear_Small ; split-pane -H -s .6 -p Arch_Retro ; mf left ; split-pane -H -s .25 -p CMD_Bottom ; mf left

### Expected Behavior

Terminal launches into 8 panes, with varying profiles.

### Actual Behavior

All terminal windows crash, including the command prompt used to launch wt.exe.

Start by running the reported wt.exe command on Windows Terminal 1.23.12811.0 and confirm whether the multi-pane sequence reproduces the crash. Trace the command-line pane-splitting and move-focus operations to identify the failure; done means the command opens eight panes with the requested profiles without crashing any terminal window.

Written by the indexing model from the issue text.