fix(dxcc): /MM and /AM belong to no entity

RI1FJL/MM resolved to Franz Josef Land while the expedition was still sailing
there, telling the operator they had worked an entity they had not.

The old behaviour was deliberate — the comment read "strict DXCC says no
entity, but the log should still show the operator's country" — and that is
wrong for exactly this reason. A home country on a maritime mobile is not extra
information; it is a false claim about where the contact happened, and it is
the kind of false claim that gets a QSO submitted for an award it cannot win.

Trailing only. A LEADING "MM" is the Scotland prefix and "AM" is Spain, so
MM0ABC and AM5X keep their entities — getting that wrong would be a far larger
error than the one being fixed. /P, /M and /B are unaffected: a portable
station is still ashore.

In the cluster the column says "Maritime mobile — no DXCC" rather than going
blank, because blank is what an UNRESOLVED spot looks like and the two mean
opposite things — one is "we don't know yet", this is "there is nothing to
know". Display only: the QSO's own Country stays empty, since that field holds
a DXCC entity name and there is none.

changelog.json

@@ -10,7 +10,8 @@
       "Station Control: the short and long path headings are repeated under the compass, at a readable size and clickable.",
       "Compact mode: the window now fits the entry strip instead of leaving a band of empty space below it.",
       "HRDLog: an ON AIR option publishes your live frequency, mode and rig on hrdlog.net.",
-      "ADIF: the county is exported as STATE,COUNTY as the standard requires, and a county imported that way now fills the state too."
+      "ADIF: the county is exported as STATE,COUNTY as the standard requires, and a county imported that way now fills the state too.",
+      "A /MM or /AM callsign no longer resolves to a country — RI1FJL/MM read as Franz Josef Land while the expedition was still sailing there."
     ],
     "fr": [
       "Cluster : « Masquer les contactés » ne masque plus un spot qui est un nouveau préfixe, comté, carré ou parc dans une contrée déjà faite.",
@@ -20,7 +21,8 @@
       "Contrôle station : les azimuts court et long chemin sont repris sous la boussole, lisibles et cliquables.",
       "Mode compact : la fenêtre épouse la bande de saisie au lieu de laisser une bande vide en dessous.",
       "HRDLog : une option ON AIR publie ta fréquence, ton mode et ta radio en direct sur hrdlog.net.",
-      "ADIF : le comté est exporté sous la forme ÉTAT,COMTÉ comme l exige le standard, et un comté importé ainsi remplit aussi l état."
+      "ADIF : le comté est exporté sous la forme ÉTAT,COMTÉ comme l exige le standard, et un comté importé ainsi remplit aussi l état.",
+      "Un indicatif en /MM ou /AM ne se résout plus en pays — RI1FJL/MM affichait Franz Josef Land alors que l expédition faisait encore route."
     ]
   },
   {