The TUI has always raised `KillConfirm` before `x` kills anything; the web
sent `DELETE /api/sessions/:id` on the first press and only prompted when the
daemon refused. The command bar puts both behind the same three keystrokes,
so the difference now reads as a bug (#160).
The web follows the TUI: a kill is destructive and unattended agents live in
these sessions. `killDialog.ts` grows a confirmation that shares the force
prompt's shell, names the blockers the card already knows about, and keeps the
focus on Cancel. The guarded refusal still opens its own dialog behind it.
The kill button now sends the unforced DELETE immediately instead of
asking first. Only the daemon's guard refusal raises a prompt, and it is
a real dialog rather than confirm(), so it can offer the override the
daemon already implements.
The API error envelope is decoded into ApiRequestError, keeping the code
and the unsaved-work breakdown so the dialog names what is in the way.