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/app.js

@@ -4669,6 +4669,26 @@ function createTargetCard(target, deviceMap, sourceMap) {
                         <div class="metric-value">${metrics.errors_count || 0}</div>
                     </div>
                 </div>
+                ${state.timing_total_ms != null ? `
+                <div class="timing-breakdown">
+                    <div class="timing-header">
+                        <div class="metric-label">${t('device.metrics.timing')}</div>
+                        <div class="timing-total"><strong>${state.timing_total_ms}ms</strong></div>
+                    </div>
+                    <div class="timing-bar">
+                        <span class="timing-seg timing-extract" style="flex:${state.timing_extract_ms}" title="extract ${state.timing_extract_ms}ms"></span>
+                        <span class="timing-seg timing-map" style="flex:${state.timing_map_leds_ms}" title="map ${state.timing_map_leds_ms}ms"></span>
+                        <span class="timing-seg timing-smooth" style="flex:${state.timing_smooth_ms || 0.1}" title="smooth ${state.timing_smooth_ms}ms"></span>
+                        <span class="timing-seg timing-send" style="flex:${state.timing_send_ms}" title="send ${state.timing_send_ms}ms"></span>
+                    </div>
+                    <div class="timing-legend">
+                        <span class="timing-legend-item"><span class="timing-dot timing-extract"></span>extract ${state.timing_extract_ms}ms</span>
+                        <span class="timing-legend-item"><span class="timing-dot timing-map"></span>map ${state.timing_map_leds_ms}ms</span>
+                        <span class="timing-legend-item"><span class="timing-dot timing-smooth"></span>smooth ${state.timing_smooth_ms}ms</span>
+                        <span class="timing-legend-item"><span class="timing-dot timing-send"></span>send ${state.timing_send_ms}ms</span>
+                    </div>
+                </div>
+                ` : ''}
                 ` : ''}
             </div>
             <div class="card-actions">