v0.2.0

Upgrade notes

• Upgrading the hub adds a disk_stat table to the timeseries database on
  start. Agents from v0.1.x keep working and already send disk usage.
• To move an agent you run by hand to the systemd service, stop it and run
  curl -fsSL https://vpspilot.dev/install-agent.sh | sudo sh -s -- --hub <hub>:55001.
  If it used the default state file (/var/lib/vps-pilot-agent/state.json),
  it keeps its enrollment and needs no token. Otherwise use the command from
  Re-enroll agent.

Added

• Disk usage: the hub stores the root filesystem's percent used, the
  Metrics tab charts it, and alerts can watch it (Disk metric). Agents
  already sent it, so they don't need upgrading.
• Nodes show whether their agent is connected: Online, or Offline
  with when it was last seen, on the node page and the node list.
• One-line agent install: Nodes → Add node shows a command that runs
  https://vpspilot.dev/install-agent.sh. It installs the agent release
  matching the hub, checks it against SHA256SUMS, sets it up as a systemd
  service, enrolls it, and removes the token from disk. Running it again
  upgrades the agent.
• Agent .deb packages for amd64 and arm64, with the systemd unit.
• Agent release archives include the systemd unit,
  vps-pilot-agent.service.

Changed

• The dashboard sidebar shows the VPS Pilot wordmark instead of a
  placeholder icon and "Enterprise".