Starts a per-release changelog. The Unreleased section captures everything
merged since v1.3.0 (ssh-mcp v2 support, sidecar detect/edit, version pin,
permission pre-flight, hot-reload, light theme, visible update checker,
move-to-env, cross-client phase 1) with the ssh-mcp-is-breaking-upstream /
BCC-is-additive distinction called out. Past releases backfilled from tags.
