Biplane v1.3.8 — first public release

Biplane takes off: native Wheel + Traveler panels, git-driven ticket automation (commit → In Progress, PR → In Review, merge → Done), signed audit ledger, watch-mode boards (change-gated, flicker-free), Biplane branding + about box crediting Plane.

Built on Plane v1.3.1 Community (AGPL-3.0) — thank you, Plane team.