Reposition tiles on an xTiles page (view). Provide viewId and a list of tiles with their new grid positions (x, y, w, h). Only the listed tiles move; the rest keep their current position. Coordinates use the xTiles grid — (x, y) is the top-left corner and (w, h) the size, in grid cells. Out-of-bounds or overlapping positions are rejected. Returns the resulting full layout. Tip: call xtiles_get_page_layout first to get tile IDs and current positions. Which colours, styles, sizes and positions to use: xtiles://guide/markdown/design.