Shell state of opened file descriptor is not captured by `hs`

For speculation to work properly `hs` needs to have the ability to capture, squash, and apply state changes. The shell has the ability to open file descriptors and such state cannot be tracked by `hs`. For example:

```bash
exec 3> file1
echo hello >&3
cat file1
```

After `hs` start executing the second command it will not have file descriptor 3 correctly opened as file1. This behavior is needed for git's CI to work.

No files or tests are named. Start by locating the code that implements hs speculation and state capture, then reproduce the shown exec and redirection sequence. Done means file descriptor 3 remains opened as file1 across speculative execution, including the stated git CI use case.

Written by the indexing model from the issue text.