fix(dashboard): soften the pivot into 'but you have traveled' + audio review fixes

The transition out of the fear act was too brutal: the silence now arrives as
a fast pull-away with the hall tail ringing out instead of a 100ms kill, the
pivot line trades its impact boom for a slow warm A1 swell (the first calm
breath), and the line itself breathes in over 3.4s.

Audio review fixes: the wind's swell LFO moves to a series tremolo stage so
the release can actually silence it before the cut (it used to warble through
the silence and click on stop); the heartbeat's noise layer becomes the
intended high-passed click instead of a dull lowpassed thud; dispose() pulls
the master to zero before the deferred context close so leaving the show
cannot pop.

client/src/components/FourZero/fourzero.css

@@ -66,6 +66,11 @@
   letter-spacing: 0.01em;
 }
 
+/* The pivot line out of the silence breathes in slowly instead of arriving. */
+.fz-line-soft {
+  animation-duration: 3.4s;
+}
+
 @keyframes fzLineIn {
   from { opacity: 0; transform: translateY(14px); filter: blur(6px); }
   to { opacity: 1; transform: translateY(0); filter: blur(0); }