Use Firecracker SDK in daemon

Replace the daemon's hand-rolled Firecracker process/socket client with the official firecracker-go-sdk while keeping the existing VM lifecycle and host-side disk and TAP setup intact.

Build machine configs through the SDK, launch Firecracker through a sudo process runner, resolve the real VM PID after startup, and use the SDK client for Ctrl-Alt-Del instead of raw REST calls. Drop the unused cached Firecracker state and add focused adapter tests for config and process-runner wiring.

Validated with go mod tidy, go test ./..., and make build. A live KVM/Firecracker smoke boot was not run in this environment.

internal/firecracker/client_test.go

@@ -0,0 +1,78 @@
+package firecracker
+
+import (
+	"context"
+	"testing"
+)
+
+func TestBuildConfig(t *testing.T) {
+	cfg := buildConfig(MachineConfig{
+		VMID:            "vm-1",
+		SocketPath:      "/tmp/fc.sock",
+		LogPath:         "/tmp/fc.log",
+		MetricsPath:     "/tmp/fc.metrics",
+		KernelImagePath: "/kernel",
+		InitrdPath:      "/initrd",
+		KernelArgs:      "console=ttyS0",
+		RootDrivePath:   "/dev/mapper/root",
+		WorkDrivePath:   "/var/lib/banger/root.ext4",
+		TapDevice:       "tap-fc-1",
+		VCPUCount:       4,
+		MemoryMiB:       2048,
+	})
+
+	if cfg.SocketPath != "/tmp/fc.sock" {
+		t.Fatalf("socket path = %q", cfg.SocketPath)
+	}
+	if cfg.LogPath != "/tmp/fc.log" || cfg.MetricsPath != "/tmp/fc.metrics" {
+		t.Fatalf("unexpected log or metrics path: %+v", cfg)
+	}
+	if cfg.KernelImagePath != "/kernel" || cfg.InitrdPath != "/initrd" {
+		t.Fatalf("unexpected kernel paths: %+v", cfg)
+	}
+	if len(cfg.Drives) != 2 {
+		t.Fatalf("drive count = %d, want 2", len(cfg.Drives))
+	}
+	if cfg.Drives[0].DriveID == nil || *cfg.Drives[0].DriveID != "work" {
+		t.Fatalf("work drive id = %v", cfg.Drives[0].DriveID)
+	}
+	if cfg.Drives[1].DriveID == nil || *cfg.Drives[1].DriveID != "rootfs" {
+		t.Fatalf("root drive id = %v", cfg.Drives[1].DriveID)
+	}
+	if len(cfg.NetworkInterfaces) != 1 {
+		t.Fatalf("interface count = %d, want 1", len(cfg.NetworkInterfaces))
+	}
+	if got := cfg.NetworkInterfaces[0].StaticConfiguration.HostDevName; got != "tap-fc-1" {
+		t.Fatalf("host dev name = %q", got)
+	}
+	if cfg.MachineCfg.VcpuCount == nil || *cfg.MachineCfg.VcpuCount != 4 {
+		t.Fatalf("vcpu = %v", cfg.MachineCfg.VcpuCount)
+	}
+	if cfg.MachineCfg.MemSizeMib == nil || *cfg.MachineCfg.MemSizeMib != 2048 {
+		t.Fatalf("memory = %v", cfg.MachineCfg.MemSizeMib)
+	}
+	if cfg.MachineCfg.Smt == nil || *cfg.MachineCfg.Smt {
+		t.Fatalf("smt = %v, want false", cfg.MachineCfg.Smt)
+	}
+}
+
+func TestBuildProcessRunnerUsesSudoWrapper(t *testing.T) {
+	cmd := buildProcessRunner(context.Background(), MachineConfig{
+		BinaryPath: "/repo/firecracker",
+		SocketPath: "/tmp/fc.sock",
+		VMID:       "vm-1",
+	}, nil)
+
+	if cmd.Path != "/usr/bin/sudo" && cmd.Path != "sudo" {
+		t.Fatalf("command path = %q", cmd.Path)
+	}
+	if len(cmd.Args) != 5 {
+		t.Fatalf("args = %v", cmd.Args)
+	}
+	if cmd.Args[1] != "-n" || cmd.Args[2] != "sh" || cmd.Args[3] != "-c" {
+		t.Fatalf("args = %v", cmd.Args)
+	}
+	if want := "umask 000 && exec '/repo/firecracker' --api-sock '/tmp/fc.sock' --id 'vm-1'"; cmd.Args[4] != want {
+		t.Fatalf("script = %q, want %q", cmd.Args[4], want)
+	}
+}