Lg1: Implement both light|darkAmbience stimBuffs & their production

We now produce both light and dark ambience stimframes into
stimbuffs for the LivoxGen1 lidar devices.

devices/avia0.dapss

@@ -4,16 +4,21 @@
 
 +edev|avia0|mesh()|livoxGen1()|livoxProto1(SMO_IP)|3JEDK380010Z39||
 +edev|avia0|pcloudIntensity()|livoxGen1()|livoxProto1(SMO_IP)|3JEDK380010Z39||
-/* pcloudAmbience with:
- * - postrin: be positively disposed to dim ambience (low passband counts),
- *   but don't be so positively drawn that your eyelids droop and your pupils
- *   dilate, in human terms (i.e: no distraction). And no stupefaction either.
- * - negtrin: be negatively disposed to high ambience (high passband counts),
- *   to the point of feeling un-ignorable pain when it's sufficiently high.
+
+/* pcloudLightAmbience with negtrin: be negatively disposed to high ambience
+ * (high passband counts above passband-count-gt-val), to the point of feeling
+ * un-ignorable pain when it's sufficiently high.
  */
-+edev|avia0|
-	postrin(interest-pc=85)|
-	negtrin(interest-pc=85|distraction-pc=90|intolerable-pc=95)|
-	pcloudAmbience(passband-count-lt-val=8|passband-count-gt-val=120)|
-	livoxGen1()|livoxProto1(SMO_IP)|
-	3JEDK380010Z39||
++edev|avia0
+	|negtrin(interest-pc=85|distraction-pc=90|intolerable-pc=95)
+	|pcloudLightAmbience(passband-count-gt-val=120)
+	|livoxGen1()|livoxProto1(SMO_IP)|3JEDK380010Z39||
+
+/* pcloudDarkAmbience with postrin: be positively disposed to dim ambience
+ * (passband counts below passband-count-lt-val), but not so drawn that eyelids
+ * droop — no distraction, no stupefaction.
+ */
++edev|avia0
+	|postrin(interest-pc=85)
+	|pcloudDarkAmbience(passband-count-lt-val=8)
+	|livoxGen1()|livoxProto1(SMO_IP)|3JEDK380010Z39||