Assign AI/BI dashboard positions from one map and check the grid

When a Databricks Lakeview dashboard JSON is generated by a script, keep widget definitions free of layout and assign every position afterwards from a single POSITIONS dict keyed by widget name. Then sort the layout by (y, x). Rearranging sections, for example pairing each chart with its table instead of stacking tables at the bottom, becomes a one-place edit. Validate the result by filling a 12-column cell map: assert that no cell is claimed twice and that no cell is left empty up to the last row. This catches overlaps and gaps before deploying.