feat: add Attributes column to Dashboard exchanges table

Shows up to 2 attribute badges (color="auto") per row with a +N overflow
indicator; empty rows render a muted dash. Uses CSS module classes only.

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

ui/src/pages/Dashboard/Dashboard.module.css

@@ -239,6 +239,22 @@
   opacity: 1;
 }
 
+/* Attributes cell in table */
+.attrCell {
+  display: flex;
+  gap: 4px;
+  align-items: center;
+}
+
+.attrOverflow {
+  font-size: 10px;
+  color: var(--text-muted);
+}
+
+.muted {
+  color: var(--text-muted);
+}
+
 /* Open full details link in panel */
 .openDetailLink {
   background: transparent;