feat: expand appearance with shader effects and new style presets

Add 5 WebGL shader background effects (Aurora, Plasma, Digital Rain,
Starfield, Warp Tunnel) via a new bg-shaders.ts engine that shares
a dedicated canvas. Add 5 style presets (Sakura, Ocean, Copper, Vapor,
Monolith) with distinctive font pairings. Remove CSS particles effect
in favor of shader-based alternatives. Fix dot grid visibility and
tune all shader intensities for subtle ambient appearance.

server/src/wled_controller/static/locales/ru.json

@@ -1751,15 +1751,24 @@
     "appearance.preset.arctic": "Арктика",
     "appearance.preset.terminal": "Терминал",
     "appearance.preset.neon": "Неон",
+    "appearance.preset.sakura": "Сакура",
+    "appearance.preset.ocean": "Океан",
+    "appearance.preset.copper": "Медь",
+    "appearance.preset.vapor": "Вейпорвейв",
+    "appearance.preset.monolith": "Монолит",
     "appearance.preset.applied": "Стиль применён",
     "appearance.bg.label": "Фоновые эффекты",
     "appearance.bg.hint": "Добавьте фоновый слой за интерфейсом.",
     "appearance.bg.none": "Нет",
     "appearance.bg.noise": "Шумовое поле",
+    "appearance.bg.aurora": "Северное сияние",
+    "appearance.bg.plasma": "Плазма",
+    "appearance.bg.rain": "Цифровой дождь",
+    "appearance.bg.stars": "Звёздное поле",
+    "appearance.bg.warp": "Тоннель",
     "appearance.bg.grid": "Точечная сетка",
     "appearance.bg.mesh": "Градиент",
     "appearance.bg.scanlines": "Развёртка",
-    "appearance.bg.particles": "Частицы",
     "appearance.bg.applied": "Фоновый эффект применён",
 
     "color_strip": {