The trail reads as motion, never as residue: the ghosts fade with the sprint

The lingering doubles were a real bug, not a taste problem: racketAI's
!incoming return kept the last chase's vx/vz on the body, so the speed
ghosts trailed a zombie that had already stopped. The velocity dies with
the chase now (tested). The look is halved with it: ghost alphas
0.22/0.10 -> 0.11/0.05, trailK 0.05 -> 0.035 — a hint of speed in the
corner of the eye, never a second body.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/config.js

@@ -622,7 +622,8 @@ export const TUNE = {
   // back along the velocity). Procedural register only — dust and afterimage, never painted into
   // a sprite, and nothing draws at walking pace: trailMin sits above every shamble.
   trailMin: 3.6,       // m/s of ground speed before a body earns dust + ghosts (0 = both off)
-  trailK: 0.05,        // s each ghost trails behind along the velocity (two samples: 1x and 2x)
+  trailK: 0.035,       // s each ghost trails behind along the velocity (two samples: 1x and 2x).
+                       // 0.05 on the first cut — "der Effekt sollte dezenter sein": shorter smear
   runDustEvery: 0.5,   // m of ground covered per dust puff while sprinting
   fps: 60,          // frame cap — 30 halves battery/heat but Oliver felt it; smoothness wins (0 = uncapped)
   lowPower: 1,      // >= 0.5 caps RES at 3 (−44% of pixels painted per frame) — the battery saver,