feat(trails): render authoritative player route trails

docs/PLAYER_UI.md

@@ -94,6 +94,10 @@ received cells. It hashes each visible edge deterministically to choose the
 approved local SVG variant, so the browser neither retains unseen geometry nor
 decides topology. The layer is decorative and cannot receive input.
 
+Each complete projection also replaces one bounded SVG trail layer. It draws
+only server-authorized visible east/south passage masks: yellow and blue use
+different dotted rhythms, and a shared passage retains both patterns.
+
 All remaining Russian system messages use one `role=status` live message rail
 above the application top bar. One connection-loss message has highest priority
 and remains until a successful recovery; other messages deduplicate, replace