Add profile conditions, scene presets, MQTT integration, and Scenes tab

Feature 1 — Profile Conditions: time-of-day, system idle (Win32
GetLastInputInfo), and display state (GUID_CONSOLE_DISPLAY_STATE)
condition types for automatic profile activation.

Feature 2 — Scene Presets: snapshot/restore system that captures target
running states, device brightness, and profile enables. Server-side
capture with 5-step activation order. Dedicated Scenes tab with
CardSection-based card grid, command palette integration, and dashboard
quick-activate section.

Feature 3 — MQTT Integration: MQTTService singleton with aiomqtt,
MQTTLEDClient device provider for pixel output, MQTT profile condition
type with topic/payload matching, and frontend support for MQTT device
type and condition editor.

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

server/src/wled_controller/static/js/features/tabs.js

@@ -19,8 +19,12 @@ function _setHash(tab, subTab) {
 }
 
 let _suppressHashUpdate = false;
+let _activeTab = null;
 
 export function switchTab(name, { updateHash = true, skipLoad = false } = {}) {
+    if (_activeTab === name) return;
+    _activeTab = name;
+
     document.querySelectorAll('.tab-btn').forEach(btn => {
         const isActive = btn.dataset.tab === name;
         btn.classList.toggle('active', isActive);
@@ -56,6 +60,8 @@ export function switchTab(name, { updateHash = true, skipLoad = false } = {}) {
             if (typeof window.loadTargetsTab === 'function') window.loadTargetsTab();
         } else if (name === 'profiles') {
             if (typeof window.loadProfiles === 'function') window.loadProfiles();
+        } else if (name === 'scenes') {
+            if (typeof window.loadScenes === 'function') window.loadScenes();
         }
     }
 }