fix: prevent dashboard top-grid cards from overflowing horizontally

Increase minimum column width from 280px to 380px so the 3-column Top
IPs table fits without clipping. Add overflow/min-width safety net for
narrow viewports.

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

internal/web/templates/layout.html

@@ -29,9 +29,13 @@
         }
         .top-grid {
             display: grid;
-            grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
+            grid-template-columns: repeat(auto-fit, minmax(380px, 1fr));
             gap: 1rem;
         }
+        .top-grid article {
+            overflow: hidden;
+            min-width: 0;
+        }
         nav h1 {
             margin: 0;
         }