feat: replace text labels with icons in runtime cards

Use Activity, Cpu, and HeartPulse icons instead of "tps", "cpu", and
"ago" text in compact and expanded app cards. Bump design-system to
v0.1.55 for sidebar footer alignment fix.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/src/pages/AgentHealth/AgentHealth.module.css

@@ -111,6 +111,12 @@
   color: var(--text-muted);
 }
 
+.groupMeta > span {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+}
+
 .groupMeta strong {
   font-family: var(--font-mono);
   color: var(--text-secondary);
@@ -319,19 +325,31 @@
 .compactCardTps {
   font-family: var(--font-mono);
   color: var(--text-muted);
+  display: inline-flex;
+  align-items: center;
+  gap: 3px;
 }
 
 .compactCardCpu {
   font-family: var(--font-mono);
   color: var(--text-muted);
+  display: inline-flex;
+  align-items: center;
+  gap: 3px;
 }
 
 .compactCardHeartbeat {
   color: var(--text-muted);
+  display: inline-flex;
+  align-items: center;
+  gap: 3px;
 }
 
 .compactCardHeartbeatWarn {
   color: var(--card-accent);
+  display: inline-flex;
+  align-items: center;
+  gap: 3px;
 }
 
 /* Wrapper for each compact grid cell — anchor for overlay */