fix: log the grid the station sent, and show the SPE going off first press

Grid: RI0FA transmitted QN35 all evening and was logged with its licence
holder's home square. WSJT-X's logged ADIF usually carries no GRIDSQUARE, so
the lookup was the only source left — and QRZ/HamQTH describe where an operator
LIVES, which for an expedition is the wrong side of the planet.

The square heard on the air is now applied before the lookup runs, so
refineGrid has something to defend. It still upgrades a 4-character square to a
6-character one from the same field, and still refuses a finer square from a
different field.

SPE: decodeCSV marks the client connected on every frame it parses, and the
poll goroutine can be mid-read while PowerOff runs. The frame from a second ago
landed after PowerOff had marked the amp offline and put it straight back,
which is why OFF had to be pressed twice.

Frames are ignored for three seconds after the off key goes out — the window is
opened before the key is sent, so nothing already travelling can beat it. Time
bounded rather than latched: an amp switched back on at its own front panel has
to reappear without being told.

changelog.json

@@ -6,13 +6,17 @@
       "Appearance: row colouring now defaults to a left stripe, with a filled row and its strength offered as choices.",
       "The band map now follows the cluster filters — LoTW only, spotter continent, hide worked, status and mode chips.",
       "Band map: stations that upload to LoTW now carry the same L badge as the cluster list, switchable in Appearance.",
-      "LoTW: contacts TQSL leaves out — already uploaded, or outside the certificate date range — are no longer reported as uploaded."
+      "LoTW: contacts TQSL leaves out — already uploaded, or outside the certificate date range — are no longer reported as uploaded.",
+      "FT8: a contact is logged with the grid the station actually sent, not the home square from QRZ — expeditions were logged in the wrong place.",
+      "SPE amplifier: switching it off is shown at once, instead of needing a second press of OFF."
     ],
     "fr": [
       "Apparence : la coloration des lignes se fait par défaut sur une barre à gauche, la ligne remplie et son intensité restant proposées.",
       "La band map suit désormais les filtres du cluster — LoTW seulement, continent du spotter, masquer les contactés, statuts et modes.",
       "Band map : les stations qui utilisent LoTW portent le même badge L que la liste du cluster, activable dans Apparence.",
-      "LoTW : les contacts que TQSL écarte — déjà envoyés, ou hors de la plage de dates du certificat — ne sont plus annoncés comme envoyés."
+      "LoTW : les contacts que TQSL écarte — déjà envoyés, ou hors de la plage de dates du certificat — ne sont plus annoncés comme envoyés.",
+      "FT8 : un contact est enregistré avec le locator réellement émis par la station, et non le carré du domicile depuis QRZ — les expéditions étaient logguées au mauvais endroit.",
+      "Amplificateur SPE : l extinction s affiche immédiatement, au lieu de demander un second appui sur OFF."
     ]
   },
   {