Optimize numpy pipeline, add per-stage timing, and auto-sync LED count

- Eliminate 5 numpy↔tuple conversions per frame in processing hot path:
  map_border_to_leds returns ndarray, inline numpy smoothing with integer
  math, send_pixels_fast accepts ndarray directly
- Fix numpy boolean bug in keepalive check (use `is not None`)
- Add per-stage pipeline timing (extract/map/smooth/send) to metrics API
  and UI with color-coded breakdown bar
- Expose device_fps from WLED health check in API schemas
- Auto-sync LED count from WLED device: health check detects changes and
  updates storage, calibration, and active targets automatically
- Use integer math for brightness scaling (uint16 * brightness >> 8)

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

server/src/wled_controller/static/style.css

@@ -962,6 +962,71 @@ input:-webkit-autofill:focus {
     color: #999;
 }
 
+/* Timing breakdown bar */
+.timing-breakdown {
+    margin-top: 8px;
+    padding: 6px 8px;
+    background: var(--bg-color);
+    border-radius: 4px;
+}
+
+.timing-header {
+    display: flex;
+    justify-content: space-between;
+    align-items: center;
+}
+
+.timing-total {
+    font-size: 0.8rem;
+    color: var(--primary-color);
+}
+
+.timing-bar {
+    display: flex;
+    height: 8px;
+    border-radius: 4px;
+    overflow: hidden;
+    margin: 4px 0;
+    gap: 1px;
+}
+
+.timing-seg {
+    min-width: 2px;
+    transition: flex 0.3s ease;
+}
+
+.timing-extract { background: #4CAF50; }
+.timing-map { background: #FF9800; }
+.timing-smooth { background: #2196F3; }
+.timing-send { background: #E91E63; }
+
+.timing-legend {
+    display: flex;
+    flex-wrap: wrap;
+    gap: 8px;
+    font-size: 0.75rem;
+    color: #999;
+    margin-top: 4px;
+}
+
+.timing-legend-item {
+    display: flex;
+    align-items: center;
+    gap: 3px;
+}
+
+.timing-dot {
+    display: inline-block;
+    width: 8px;
+    height: 8px;
+    border-radius: 2px;
+}
+
+.timing-dot.timing-extract { background: #4CAF50; }
+.timing-dot.timing-map { background: #FF9800; }
+.timing-dot.timing-smooth { background: #2196F3; }
+.timing-dot.timing-send { background: #E91E63; }
+
 /* Modal Styles */
 .modal {
     display: none;