fix(bandopen): honour the operator's band selection

The chips in Settings only ever shaped the PSK Reporter SUBSCRIPTION. Neither
feed path checked them: both asked bandopen.Watched, which says which bands the
detector is capable of and knows nothing about the selection. So the cluster
path announced every watched band regardless, and widening the subscription to
"+" for grid chasing let PSK Reporter do the same — a station with only 6 m
ticked got 10 m and 2 m badges.

The selection is now cached beside the on/off flag and checked on both paths,
and unticking a band puts its badge out: badges fade on a timer fed by spots
the detector no longer looks at, so it would otherwise stay lit until a
restart.

changelog.json

@@ -5,12 +5,14 @@
     "en": [
       "Cluster: the grid cache now holds 100,000 callsigns and rotates instead of emptying itself, so locators stop vanishing from the list.",
       "New option \"Chase new grids\": locators learnt from your decodes and from PSK Reporter are kept in their own database, with their source.",
-      "Band openings: the PSK Reporter feed is now filtered at the broker, which cuts it from about 83 messages a second to under two."
+      "Band openings: the PSK Reporter feed is now filtered at the broker, which cuts it from about 83 messages a second to under two.",
+      "Band openings: unticking a band now actually stops its announcements, and puts its badge out."
     ],
     "fr": [
       "Cluster : le cache de locators garde 100 000 indicatifs et tourne au lieu de se vider, les locators ne disparaissent donc plus de la liste.",
       "Nouvelle option « Chasse aux nouveaux carrés » : les locators appris de tes décodes et de PSK Reporter sont conservés dans leur propre base, avec leur source.",
-      "Ouvertures de bande : le flux PSK Reporter est désormais filtré chez le broker, ce qui le fait passer d environ 83 messages par seconde à moins de deux."
+      "Ouvertures de bande : le flux PSK Reporter est désormais filtré chez le broker, ce qui le fait passer d environ 83 messages par seconde à moins de deux.",
+      "Ouvertures de bande : décocher une bande arrête réellement ses annonces et éteint son badge."
     ]
   },
   {