Add an experimental Alpine image flow

Stage a complete Alpine x86_64 image stack so \	--image alpineworks like the existing manual Void path instead of relying on Debian-oriented image builds.\n\nAdd make targets plus kernel/rootfs/register helpers that download pinned Alpine artifacts, extract a Firecracker-compatible vmlinux, build a matching mkinitfs initramfs, seed OpenRC services, and register/promote a managed image named alpine.\n\nFold in the bring-up fixes discovered during boot validation: use rootfstype=ext4 in shared boot args, install libgcc/libstdc++ for the opencode binary, and give opencode more time to become ready on cold boots.\n\nValidate with go test ./..., the Alpine helper builds, image promotion, and banger vm create --image alpine --name alp --nat plus guest service and port checks.

internal/cli/cli_test.go

@@ -111,6 +111,24 @@ func TestInternalNATFlagsExist(t *testing.T) {
 	}
 }
 
+func TestInternalPackagesCommandSupportsAlpine(t *testing.T) {
+	cmd := NewBangerCommand()
+	var stdout bytes.Buffer
+	cmd.SetOut(&stdout)
+	cmd.SetArgs([]string{"internal", "packages", "alpine"})
+
+	if err := cmd.Execute(); err != nil {
+		t.Fatalf("Execute(): %v", err)
+	}
+
+	output := stdout.String()
+	for _, want := range []string{"alpine-base", "docker", "libgcc", "libstdc++", "mkinitfs", "openssh"} {
+		if !strings.Contains(output, want+"\n") {
+			t.Fatalf("output = %q, want package %q", output, want)
+		}
+	}
+}
+
 func TestVMCreateFlagsExist(t *testing.T) {
 	root := NewBangerCommand()
 	vm, _, err := root.Find([]string{"vm"})