feat(decodes): say when the decoder's band is not the rig's

A decoding application that loses its CAT link keeps announcing the last
dial frequency it knew, and every decode after that carries a stale
band. Nothing downstream can tell: the entity verdicts, the band filter
and the FT map all believe it. Seen for real — MSHV kept saying 80 m,
and Korea read as a NEW BAND because on 80 m it would have been.

Said, not decided. Taking the rig's band instead would be wrong for
anyone decoding a second receiver on another band, and a warning costs
that setup nothing but a line to read past. Shown only while CAT is
actually connected: an empty band means there is nothing to compare
with, never that the rig is on no band. Opens 0.27.9.

changelog.json

@@ -1,4 +1,14 @@
 [
+  {
+    "version": "0.27.9",
+    "date": "",
+    "en": [
+      "FT decodes warn when the decoding application announces a band the radio is not on — the signature of a lost CAT link, where it repeats the last frequency it knew and every decode after that carries a stale band. Nothing downstream could tell, so NEW BAND was being judged against a band the operator had left. OpsLog says it rather than deciding: a second receiver on another band is a real setup, and it costs that one only a line to read past."
+    ],
+    "fr": [
+      "Les FT decodes signalent quand le logiciel de décodage annonce une bande sur laquelle la radio n’est pas — la signature d’une liaison CAT perdue, où il répète la dernière fréquence connue et où tous les décodages suivants portent une bande périmée. Rien en aval ne pouvait s’en apercevoir : NOUVELLE BANDE était donc jugé sur une bande quittée. OpsLog le dit sans décider à votre place : un second récepteur sur une autre bande est une configuration légitime, et il ne lui en coûte qu’une ligne à ignorer."
+    ]
+  },
   {
     "version": "0.27.8",
     "date": "",