fix(ui): fix .app-data-table dark mode — @apply dark: unreliable in @layer components

Replace `@apply dark:bg-gray-900/95` with an explicit `:is(.dark) .app-data-table`
rule using CSS variables, matching the established pattern of `.app-surface` and
`.app-toolbar`. Fixes Allocations, ResourceTableWidget, and ProjectTableWidget
all appearing white in dark mode.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/web/src/app/globals.css

@@ -513,7 +513,14 @@
   }
 
   .app-data-table {
-    @apply overflow-hidden rounded-2xl border border-gray-200 bg-white shadow-sm dark:border-gray-700 dark:bg-gray-900/95;
+    @apply overflow-hidden rounded-2xl border border-gray-200 bg-white shadow-sm;
+  }
+
+  /* Explicit dark rule — @apply dark: inside @layer components is unreliable */
+  :is(.dark) .app-data-table {
+    background-color: rgb(var(--surface-card));
+    border-color: rgb(var(--border-subtle));
+    box-shadow: none;
   }
 
   .app-data-table table {
@@ -521,7 +528,7 @@
   }
 
   .app-data-table thead tr {
-    @apply bg-gray-50/90 dark:bg-gray-800/80;
+    @apply bg-gray-50/90;
   }
 
   :is(.dark) .app-data-table thead tr {