Exploded view remembers where you drag its windows

Ported from BT411's BT_GLASS_LAYOUT (29c502d).

The exploded view's panes are draggable desktop windows, but the
arrangement is recomputed on every launch, so dragging one somewhere
useful never survived the menu-race-menu loop.

RP412MFDLAYOUT persists it to mfd_layout.cfg beside bindings.txt:

  off / 0 / unset   computed arrangement only, no file (default)
  load / restore    restore saved positions at startup, never write
  save / adjust     restore, then rewrite on each finished drag
                    (WM_EXITSIZEMOVE) and on teardown

One "<title>=x,y,w,h" line per pane. Position is restored and the size
read and discarded: a pane's size follows its content and its button
banks, so letting an old size back in would misshape it after any
geometry change - and this port has changed that geometry twice already.

Load runs after the computed arrangement rather than instead of it, so a
pane the file does not mention simply keeps its computed spot. Only the
exploded view registers: the composited cockpit's panes are chrome-less
children with nothing to drag, so they have no position worth keeping.

RP412 needs no equivalent of BT411's "restored" flag. Its re-snap is
LayoutCockpit on WM_SIZE, which only runs in cockpit mode, so nothing
comes back later to overwrite a hand-placed window.

Verified by round trip: dragged Map to 777,333 in save mode, the file
took all six panes, and a fresh launch in load mode put it physically
back at 777,333. The harness also resized the window while moving it,
which incidentally proved the saved size really is ignored - the pane
came back correctly sized from a cfg that recorded 136x39.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

pack-dist.ps1

@@ -166,6 +166,18 @@ L4PLASMA=SCREEN
 # 480x640 - decoded exactly as the pod's VDB split them, no downscale).
 L4MFDSPLIT=1
 
+# In the exploded view (L4MFDSPLIT=2) each display is a window you can
+# drag, but the arrangement is recomputed every launch, so moving one
+# somewhere useful never survived the menu-race-menu loop. This remembers
+# it, in mfd_layout.cfg beside this file:
+#   off / 0 / unset   computed arrangement only, no file (default)
+#   load              put the panes back where they were saved
+#   save              the same, and re-save on every finished drag
+# Only positions are remembered - a pane's size follows its content and
+# its button banks, so an old size is never restored over it. Drag the
+# displays where you want them once with save, then leave it on load.
+#RP412MFDLAYOUT=off
+
 # Size of the six secondary displays in the glass cockpit, as a
 # percentage of their pod size. The pod bolted them down at one size;
 # on a big panel there is room to trade viewscreen for instrument, so