v0.2.0

Added

• Notification sinks: signed webhook, Slack and Microsoft Teams, with routes that pick
  sinks by severity and event, durable queues, retries, batching and a heartbeat.
  notify-test sends a test event to each sink.
• The monitor UI gains a peer picker, a check builder, a live probe that gates Save,
  and a Routes view with a route preview.
• collector.local_only runs the collector without tailscaled, for the Kubernetes
  ProxyGroup sidecar. The Kubernetes how-to and examples/kubernetes/ show four ways
  to inject it.
• A systemd deployment guide and example unit, a how-to for exposing the UI as a
  Tailscale Service, and a tutorial for receiving a first webhook.

Changed

• HTTP request logs are structured fields instead of a JSON string in msg.
• Audit and request logs record the tailnet caller behind tailscale serve instead
  of the proxy's loopback address.
• The example systemd unit creates the state directory with mode 0700, so the
  collector no longer warns about state_dir on first start.

Full Changelog: v0.1.0...v0.2.0