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.
Replace the shell-only user workflow with `banger` and `bangerd`: Cobra commands, XDG/SQLite-backed state, managed VM and image lifecycle, and a Bubble Tea TUI for browsing and operating VMs.\n\nKeep Firecracker orchestration behind the daemon so VM specs become persistent objects, and add repo entrypoints for building, installing, and documenting the new flow while still delegating rootfs customization to the existing shell tooling.\n\nHarden the control plane around real usage by reclaiming Firecracker API sockets for the user, restarting stale daemons after rebuilds, and returning the correct `vm.create` payload so the CLI and TUI creation flow work reliably.\n\nValidation: `go test ./...`, `make build`, and a host-side smoke test with `./banger vm create --name codex-smoke`.
