style(dashboard): tile-strip placeholder parity with live trend-card chrome

The v1.4.41 W-FRONTEND-FACTORY placeholder rendered as the per-tile
Suspense fallback shipped without the trend-card's flex column or
min-height. The all-suspend edge case (every tile suspending
simultaneously, e.g. a future RSC hoist of every cell) collapsed the
grid row to zero height and the placeholder chrome diverged from the
live tile shell by a couple of layout utilities.

Match the trend-card's container classes byte-for-byte: add flex /
min-w-0 / flex-col for chrome parity and min-h-[6rem] so the fallback
holds the row open during a synchronous all-suspend transition.
Structural Suspense test pin keys on the aria-hidden marker, not the
className, so it stays green without modification.

src/app/page.tsx

@@ -1413,7 +1413,7 @@ export default function DashboardPage() {
                       fallback={
                         <div
                           aria-hidden="true"
-                          className="bg-card border-border h-full w-full rounded-xl border p-4 md:p-6"
+                          className="bg-card border-border flex h-full min-h-[6rem] w-full min-w-0 flex-col rounded-xl border p-4 md:p-6"
                         />
                       }
                     >