feat(cluster): hold the list still while it is being read, and stop truncating filters

Two things reported together, both about a list that fights back.

The GRID froze nothing: every spot landed at the top and pushed the rest
down, so a few rows in, the callsign under the pointer had moved by the
time the click arrived. It now stops redrawing as soon as it is scrolled
away from the top and says how many spots are waiting; reaching the top
again, or clicking the notice, releases it. The arrivals are counted by
finding the frozen top row in the live list rather than by comparing
lengths — the list is a ring buffer, so once it is full a length
comparison would report nothing new for the rest of the evening.

The COMMAND BUTTONS were capped at 120 characters. A DXSpider filter
naming the prefixes an operator wants runs well past that, and the field
just stopped accepting keystrokes: the command was saved truncated with
nothing to say why. 500 now, with the full text in the tooltip since the
box cannot show it.

changelog.json

@@ -3,10 +3,14 @@
     "version": "0.26.14",
     "date": "",
     "en": [
-      "Elecraft console: the transmit meters are read whenever the RADIO says it is transmitting, not only when OpsLog keyed it. Keying with the front-panel PTT, a footswitch or the mic button left the panel showing a receiver — and the power and SWR bars are read only while transmitting, so for anyone keying by hand they were never read at all."
+      "Elecraft console: the transmit meters are read whenever the RADIO says it is transmitting, not only when OpsLog keyed it. Keying with the front-panel PTT, a footswitch or the mic button left the panel showing a receiver — and the power and SWR bars are read only while transmitting, so for anyone keying by hand they were never read at all.",
+      "Cluster: the list holds still while it is being read. Scrolled away from the top it stops redrawing and shows how many spots are waiting; scrolling back to the top, or clicking the notice, releases it. On a busy evening a spot lands every second or two and the callsign under the pointer had moved by the time the click arrived.",
+      "Cluster command buttons take 500 characters instead of 120. A DXSpider filter listing wanted prefixes runs past a hundred easily, and the field simply stopped accepting keystrokes — saving the command truncated, with nothing to say so."
     ],
     "fr": [
-      "Console Elecraft : les mesures d'émission sont lues dès que la RADIO se déclare en émission, et plus seulement quand OpsLog l'a mise en émission. Passer en émission par le PTT de façade, une pédale ou le bouton du micro laissait le panneau croire à une réception — et comme les barres de puissance et de ROS ne sont lues qu'en émission, elles ne l'étaient jamais pour qui manipule à la main."
+      "Console Elecraft : les mesures d'émission sont lues dès que la RADIO se déclare en émission, et plus seulement quand OpsLog l'a mise en émission. Passer en émission par le PTT de façade, une pédale ou le bouton du micro laissait le panneau croire à une réception — et comme les barres de puissance et de ROS ne sont lues qu'en émission, elles ne l'étaient jamais pour qui manipule à la main.",
+      "Cluster : la liste se fige pendant qu'on la lit. Dès qu'on quitte le haut, elle cesse de se redessiner et indique combien de spots attendent ; revenir en haut, ou cliquer sur l'avis, la relâche. Un soir chargé, un spot tombe toutes les une ou deux secondes et l'indicatif sous le pointeur avait bougé avant que le clic n'arrive.",
+      "Les boutons de commande du cluster acceptent 500 caractères au lieu de 120. Un filtre DXSpider qui énumère des préfixes dépasse la centaine sans peine, et le champ cessait simplement d'accepter les frappes — la commande était enregistrée tronquée, sans un mot."
     ]
   },
   {