Remove X-flip from image: map content reads normally

The user wants the original tile content (map) to be readable
normally, not X-mirrored. The X-swap arrangement (canvasX = -perp
+ ...) places east tiles on the right of the screen, so X coordinates
read naturally left to right when scanning the corridor.

Combined state:
- Map content (image): drawn with normal orientation (no X-flip)
- Arrangement: east on right, west on left (X-swap)
- Labels: drawn in normal orientation in the corners
- Y-swap: north tiles (lng=+12) at canvas top -> screen top

vendor/clouds3d.js

@@ -349,9 +349,12 @@ function drawTileAt(lng, perp, dx, dz, centerTileX, centerTileY) {
         // the corridor orientation (east tiles have their image east
         // on the left of the drawn area, west tiles on the right).
         // Labels are drawn separately in normal orientation, so the
-        // X-coordinates labels read normally.
+        // Draw image with normal orientation (no X-flip). The
-        groundCtx.drawImage(img, canvasX + GROUND_TILE_SIZE, canvasY,
+        // X-swap arrangement (canvasX = -perp + ...) already places
-            -GROUND_TILE_SIZE, GROUND_TILE_SIZE);
+        // east tiles on the right of the screen, so the X coordinates
+        // read naturally left to right when scanning the corridor.
+        groundCtx.drawImage(img, canvasX, canvasY,
+            GROUND_TILE_SIZE, GROUND_TILE_SIZE);
         groundLoadedTiles[tileX + '_' + tileY] = true;
 
         // Thin border so the user can see where one tile ends and the