chore: log the window geometry that is saved and restored

Reported as a regression — reopens on the wrong screen — but the window code is
untouched since it was verified working: the only change to main.go since is the
background colour. So the fault is in the DATA, and there was no way to see it.

Both ends now log their coordinates, plus where the window actually landed after
the un-maximise / move / re-maximise dance. That separates the cases, which need
opposite fixes: nothing was captured, something wrong was captured, or the right
corner was captured and Windows moved the window anyway.

app.go

@@ -1653,6 +1653,11 @@ func (a *App) saveWindowState() {
 		x, y := wruntime.WindowGetPosition(a.ctx)
 		ws.X, ws.Y = x, y
 	}
+	// Logged because this is the only evidence of WHAT was stored: an operator
+	// reporting "it reopens on the wrong screen" cannot tell a position that was
+	// never captured from one that was captured wrong, and the two need opposite
+	// fixes.
+	applog.Printf("window: saving %d,%d %dx%d maximised=%v compact=%v", ws.X, ws.Y, ws.Width, ws.Height, ws.Maximised, a.compact)
 	writeWindowState(a.dataDir, ws)
 }
 
@@ -1667,15 +1672,20 @@ func (a *App) restoreWindowPosition() {
 	}
 	ws, ok := readWindowState(a.dataDir)
 	if !ok {
+		applog.Printf("window: no saved geometry — opening where Windows puts it")
 		return
 	}
+	applog.Printf("window: restoring %d,%d %dx%d maximised=%v", ws.X, ws.Y, ws.Width, ws.Height, ws.Maximised)
 	// Maximised: Windows reopens it on the PRIMARY screen unless we say otherwise,
 	// so a two-screen operator lost OpsLog to the wrong monitor at every launch.
 	// Un-maximise, move to the saved corner (which names the monitor), maximise
 	// again — all while the window is still hidden, so nothing flickers.
 	if ws.Maximised {
 		if ws.X == 0 && ws.Y == 0 {
-			return // never recorded (or genuinely the primary corner) — nothing to do
+			// Either never recorded, or genuinely the primary monitor's corner —
+			// indistinguishable, and both mean "leave it to Windows".
+			applog.Printf("window: maximised with corner 0,0 — nothing to restore")
+			return
 		}
 		if !onSomeMonitor(ws.X, ws.Y, normalMinW, normalMinH) {
 			applog.Printf("window: saved maximised corner %d,%d is off every monitor — opening where Windows puts it", ws.X, ws.Y)
@@ -1684,6 +1694,8 @@ func (a *App) restoreWindowPosition() {
 		wruntime.WindowUnmaximise(a.ctx)
 		wruntime.WindowSetPosition(a.ctx, ws.X, ws.Y)
 		wruntime.WindowMaximise(a.ctx)
+		gx, gy := wruntime.WindowGetPosition(a.ctx)
+		applog.Printf("window: re-maximised at the saved corner — now at %d,%d", gx, gy)
 		return
 	}
 	if ws.Width < normalMinW || ws.Height < normalMinH || ws.Width > maxW || ws.Height > maxH {