The paper turns to match the map, because a map is wider than it is tall

Follow-up on DRV1650-SR-POSTER-EXPORT: the print came out vertical, where a horizontal map fits the shape better.

The export asked for 8.5x11 portrait unconditionally, so a landscape map was letterboxed
onto a tall sheet -- white above and below, the map small in the middle. That was the
other half of the wrong vertical aspect; the first half was the tile slicing, fixed in
859bb268.

Orientation now follows the map: landscape when the map's own container is wider than it
is tall, portrait otherwise. The PAPER is unchanged -- still 8.5x11 stock, only turned --
so the sheet stays a size printers have rather than becoming a custom one.

Measured from map.getContainer() rather than from the window, because the map may be one
pane of a composite and it is the MAP's shape being exported, not the browser's.

plugin-designs/doxa-research-map/research-map.vue

@@ -1407,7 +1407,20 @@ async function openPoster() {
       import('@map/composables/printInPlace.js'),
     ])
     const exporter = useMapPoster(() => map.value)
-    const spec = defaultPosterSpec({ widthIn: 8.5, heightIn: 11, dpi: 200, orientation: 'portrait' })
+    // ★ THE PAPER FOLLOWS THE MAP, because a map is usually wider than it is tall and a portrait sheet
+    // letterboxes it (Driver, 2026-09-28: the print came out vertical and it should "probably [be] a
+    // horizontal map"). Same 8.5x11 stock either way — only the ORIENTATION turns, so the sheet is
+    // still a standard page and not a custom size no printer has.
+    // Measured from the map's own container rather than from the window: the map may be one pane of a
+    // composite, and it is the MAP's shape being exported, not the browser's.
+    const mapEl = map.value?.getContainer?.() || null
+    const landscape = !!mapEl && mapEl.clientWidth > mapEl.clientHeight
+    const spec = defaultPosterSpec({
+      widthIn:  landscape ? 11 : 8.5,
+      heightIn: landscape ? 8.5 : 11,
+      dpi: 200,
+      orientation: landscape ? 'landscape' : 'portrait',
+    })
     // The poster is titled by the VIEW on screen ("Prayer", "Religion"…), in the reader's language.
     // The legend's title bar is the fallback only: on a flat tab it is the generic word "Legend".
     const title = tabLabel(activeTab.value) || legendTitle.value || 'Doxa Map'