Add FPS sparkline chart to target cards, move timing breakdown inline

Replace the three FPS text labels (actual/current/target) with a
Chart.js sparkline chart + compact label, matching the dashboard style.
FPS history (30 samples) persists across poll rebuilds. Pipeline timing
breakdown moved inside the metrics grid directly under the FPS chart.

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

server/src/wled_controller/static/css/cards.css

@@ -519,6 +519,36 @@ ul.section-tip li {
     color: #999;
 }
 
+/* Target FPS sparkline row */
+.target-fps-row {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    grid-column: 1 / -1;
+    padding: 3px 8px;
+    background: var(--bg-color);
+    border-radius: 4px;
+}
+
+.target-fps-sparkline {
+    position: relative;
+    flex: 1;
+    min-width: 0;
+    overflow: hidden;
+    height: 36px;
+}
+
+.target-fps-label {
+    flex-shrink: 0;
+    text-align: right;
+}
+
+.target-fps-target {
+    font-weight: 400;
+    opacity: 0.5;
+    font-size: 0.75rem;
+}
+
 /* Timing breakdown bar */
 .timing-breakdown {
     margin-top: 8px;