Expose device brightness as HA number entity

Add a Number platform to the HAOS integration so each LED target
with a brightness-capable device gets a 0-255 slider in Home
Assistant. Coordinator now fetches device list and brightness on
each poll cycle. Also enable chart animation in perf-charts.

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

server/src/wled_controller/static/js/features/perf-charts.js

@@ -77,7 +77,7 @@ function _createChart(canvasId, color, fillColor) {
         options: {
             responsive: true,
             maintainAspectRatio: false,
-            animation: false,
+            animation: true,
             plugins: { legend: { display: false }, tooltip: { enabled: false } },
             scales: {
                 x: { display: false },