contrails: add jagged edges and restore 5 minute lifetime

config.js

@@ -206,7 +206,7 @@ window.CONFIG = {
         // above contrailStartKm, visible for contrailLifeS seconds.
         contrailChance: 1.00,
         contrailStartKm: 4,
-        contrailLifeS: 600,
+        contrailLifeS: 300,
         contrailWidthM: 1400,     // full trail width
         contrailFadeKm: 300,      // fully faded at this distance (ramp starts at 35 %)
         // Night contrast: a physically scaled contrail is a faint grey thread