Add Go daemon-driven VM control plane

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`.

internal/api/types.go

@@ -0,0 +1,81 @@
+package api
+
+import "banger/internal/model"
+
+type Empty struct{}
+
+type PingResult struct {
+	Status string `json:"status"`
+	PID    int    `json:"pid"`
+}
+
+type ShutdownResult struct {
+	Status string `json:"status"`
+}
+
+type VMCreateParams struct {
+	Name              string `json:"name,omitempty"`
+	ImageName         string `json:"image_name,omitempty"`
+	VCPUCount         int    `json:"vcpu_count,omitempty"`
+	MemoryMiB         int    `json:"memory_mib,omitempty"`
+	SystemOverlaySize string `json:"system_overlay_size,omitempty"`
+	WorkDiskSize      string `json:"work_disk_size,omitempty"`
+	NATEnabled        bool   `json:"nat_enabled,omitempty"`
+	NoStart           bool   `json:"no_start,omitempty"`
+}
+
+type VMRefParams struct {
+	IDOrName string `json:"id_or_name"`
+}
+
+type VMSetParams struct {
+	IDOrName     string `json:"id_or_name"`
+	VCPUCount    *int   `json:"vcpu_count,omitempty"`
+	MemoryMiB    *int   `json:"memory_mib,omitempty"`
+	WorkDiskSize string `json:"work_disk_size,omitempty"`
+	NATEnabled   *bool  `json:"nat_enabled,omitempty"`
+}
+
+type VMListResult struct {
+	VMs []model.VMRecord `json:"vms"`
+}
+
+type VMShowResult struct {
+	VM model.VMRecord `json:"vm"`
+}
+
+type VMStatsResult struct {
+	VM    model.VMRecord `json:"vm"`
+	Stats model.VMStats  `json:"stats"`
+}
+
+type VMLogsResult struct {
+	LogPath string `json:"log_path"`
+}
+
+type VMSSHResult struct {
+	Name    string `json:"name"`
+	GuestIP string `json:"guest_ip"`
+}
+
+type ImageBuildParams struct {
+	Name       string `json:"name,omitempty"`
+	BaseRootfs string `json:"base_rootfs,omitempty"`
+	Size       string `json:"size,omitempty"`
+	KernelPath string `json:"kernel_path,omitempty"`
+	InitrdPath string `json:"initrd_path,omitempty"`
+	ModulesDir string `json:"modules_dir,omitempty"`
+	Docker     bool   `json:"docker,omitempty"`
+}
+
+type ImageRefParams struct {
+	IDOrName string `json:"id_or_name"`
+}
+
+type ImageListResult struct {
+	Images []model.Image `json:"images"`
+}
+
+type ImageShowResult struct {
+	Image model.Image `json:"image"`
+}