The Go control plane already exposed banger vm kill and daemon-side kill handling, but the API package was missing the VMKillParams request type. That left the worktree depending on an unstaged type addition even though the rest of the feature was already wired.
Add the missing request struct so the CLI, RPC layer, and daemon share an explicit payload for signal-based VM termination. This commit is intentionally narrow because the rest of the kill-path work was already present.