fix: restore translucent dashboard styling (#6664)

* fix: restore translucent dashboard styling

* fix: restore dashboard widget transparency

* fix: address dashboard review feedback

* fix: apply board opacity to containers

* fix: flatten demo board container

* fix: default board roundness to sm

* fix: restore assistant widget transparency

* Revert "fix: default board roundness to sm"

This reverts commit c235cbdf2b.

* fix: address remaining dashboard review comments

* test: align grid geometry expectations

apps/nextjs/src/components/board/sections/grid/section-grid.module.css

@@ -46,12 +46,14 @@
 
 .contentMount {
   position: absolute;
-  inset: 0;
-  width: 100%;
-  height: 100%;
+  inset: var(--board-grid-item-inset, 0px);
   overflow: visible;
 }
 
+.staticItem:has([data-board-container-label]) {
+  z-index: 2;
+}
+
 .editorEntry {
   overflow: visible;
   cursor: grab;