Use vm/ instead of the hidden .vm/ as the default state directory

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

run-ubuntu2604.py

@@ -53,7 +53,7 @@ else:
     base_image = Path(result.stdout.rstrip("\n"))
     uses_shared_base_image = True
 
-state_dir = Path(env("UBUNTU_VM_STATE_DIR") or script_dir / ".vm" / "ubuntu2604")
+state_dir = Path(env("UBUNTU_VM_STATE_DIR") or script_dir / "vm" / "ubuntu2604")
 disk_size = env("UBUNTU_VM_DISK_SIZE") or "20G"
 
 
@@ -125,7 +125,7 @@ def usage(stream=sys.stdout):
 Usage: {Path(sys.argv[0]).name} [--daemon] [--download-only] [--state-dir DIR] [-- QEMU_ARGUMENT ...]
 
 Start an Ubuntu 26.04 LTS cloud image virtual machine. A writable overlay is
-created in the state directory (default: .vm/ubuntu2604/), so the downloaded
+created in the state directory (default: vm/ubuntu2604/), so the downloaded
 base image is never modified. The VM hardware (memory, CPUs, SSH port forward,
 ...) is defined in qemu/ubuntu2604.ini, which is rendered to qemu.ini in the
 state directory and loaded with QEMU's -readconfig, followed by
@@ -136,13 +136,13 @@ Options:
   --daemon         Run in the background while keeping the graphical window
   --download-only  Download the base image if it is missing, then exit
   --state-dir DIR  Directory for the VM disk, seed ISO and runtime files
-                   (default: .vm/ubuntu2604; overrides UBUNTU_VM_STATE_DIR)
+                   (default: vm/ubuntu2604; overrides UBUNTU_VM_STATE_DIR)
   -h, --help       Show this help
 
 Environment variables:
   UBUNTU_VM_BASE_IMAGE     Base qcow2 image path (default: resolved by shared image helper)
   UBUNTU_VM_SEED_IMAGE     cloud-init seed ISO path (default: alongside the VM disk)
-  UBUNTU_VM_STATE_DIR      Runtime state directory (default: .vm/ubuntu2604)
+  UBUNTU_VM_STATE_DIR      Runtime state directory (default: vm/ubuntu2604)
   UBUNTU_VM_DISK_IMAGE     Writable overlay path
   UBUNTU_VM_DISK_SIZE      New overlay virtual capacity (default: 20G)
   VM_IMAGE_ARCH            Guest/host architecture: arm64 or amd64 (default: auto-detected from the host)