feat(reports): streamline reader actions and center export dialog

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

frontend/src/app/globals.css

@@ -3866,7 +3866,7 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 .report-center-delete-confirm p { margin: 0; }
 .report-center-delete-confirm button, .report-center-menu button { min-height: 44px; }
 
-/* Native modal in the report's content column, never over the navigation rail. */
+/* Native modal: narrow screens keep the content-column sheet; desktop centers in the viewport. */
 .report-export-drawer {
   --report-export-sidebar: 0px;
   position: fixed;
@@ -3892,6 +3892,17 @@ input:not([type="radio"]):not([type="checkbox"]):not([class^="ant-"]):not([class
 @supports (height: 1dvh) {
   .report-export-drawer, .report-export-panel { max-height: 70dvh; }
 }
+/* After the narrow-screen dvh upgrade so it cannot cap desktop at 70dvh. */
+@media (min-width: 860px) {
+  .report-export-drawer {
+    inset: 0;
+    width: min(720px, 92vw);
+    max-height: 80vh;
+    margin: auto;
+    border-radius: var(--radius-lg);
+  }
+  .report-export-panel { max-height: calc(80vh - 2px); }
+}
 .report-export-header, .report-export-footer { padding: var(--space-4); flex-shrink: 0; }
 .report-export-heading { display: flex; align-items: center; justify-content: space-between; gap: var(--space-2); }
 .report-export-heading h2 { margin: 0; font-size: var(--type-title-lg); }