bash hook: nothing is captured with VS Code's shell integration loaded after it #52

With VS Code's bash shell integration loaded after the codigest hook (VS Code sources it after ~/.bashrc), no command is captured.

Cause: VS Code chains an existing DEBUG trap but runs it only for the first DEBUG event of each command line (__vsc_preexec_all, guarded by __vsc_in_command_execution). bash also runs the DEBUG trap for a bind -x handler, and the hook marks the line with one (__cdg_mark on Enter). That first event is the handler, before __cdg_mark has opened the capture, so __cdg_debug never sees the command itself and the capture never starts. VS Code's own preexec also fires at the handler instead of the command.

To reproduce: in an interactive bash --norc -i with cdg on PATH, source src/codigest/shell/hook.sh, then VS Code's script (code --locate-shell-integration-path bash), then run any command: it is not captured. tests/test_hook_terminal.py::test_bash_vscode_integration_sees_the_typed_line shows it.

Possible fixes: start the capture without relying on the next DEBUG event once a line is marked, or let the Enter handler leave other preexec frameworks' state as it found it. bash-preexec ignores bind -x handlers, so the same conflict may not appear there; not checked.