fix(window): check the saved position against the monitors, not their bounding box

Reported from a multi-monitor station: window.json held x=-7680 and the
window opened where nobody could see it, with no way back short of
editing the file — which nobody knows to do.

The guard existed but asked the wrong question. It tested the position
against the VIRTUAL SCREEN, the rectangle spanning every monitor, and
monitors rarely tile that rectangle: a wide screen beside a tall one, or
one mounted higher, leaves gaps inside the box that belong to no monitor.
A window in a gap passes a bounding-box test and is invisible. The test
now walks the monitors themselves, through EnumDisplayMonitors, and uses
each one's WORK area — a title bar under the taskbar cannot be dragged
either.

A position that is genuinely lost is now MOVED onto the nearest monitor,
keeping the window's size. Handing it back to Windows lost the size too
and dropped the window on the primary screen wherever Windows chose.

The arithmetic is in screenclamp.go with no Win32 in it, and tested
against the reporter's four-monitor layout and against a gap between two:
this fault is invisible by definition and cannot be reproduced without
the reporter's screens, so a table test is the only place it can be held.
The layout is also logged at every start, since the first question after
'OpsLog does not open' is what the screens looked like.

changelog.json

@@ -5,12 +5,14 @@
     "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.",
       "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."
+      "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.",
+      "Multi-monitor: the saved window position is now checked against the monitors themselves, not the rectangle that spans them. Monitors rarely fill that rectangle, and a window in one of the leftover gaps passed the old test while being invisible. A position that is genuinely lost is moved onto the nearest screen — keeping the window size — instead of being handed back to Windows, and the screen layout is written to the log at every start."
     ],
     "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.",
       "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."
+      "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.",
+      "Multi-écrans : la position enregistrée est désormais vérifiée contre les écrans eux-mêmes, et non contre le rectangle qui les englobe. Les écrans remplissent rarement ce rectangle, et une fenêtre tombée dans un des trous passait l'ancien test tout en étant invisible. Une position réellement perdue est déplacée sur l'écran le plus proche — en conservant la taille de la fenêtre — au lieu d'être rendue à Windows, et la disposition des écrans est écrite dans le journal à chaque démarrage."
     ]
   },
   {