Paints a CanvasDoc — group frames behind, edges with arrowheads, then
node cards (text / file / link) — fitted by a shared pan/zoom CanvasViewport
so a later hit-test lands on what's drawn. Node colours come from the file
(Obsidian presets 1..6 or hex), not clide tokens, since a .canvas is
arbitrary content; only the chrome is themed. Read-only for now; selection,
drag, and edit affordances follow.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>