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/en.json

@@ -1749,15 +1749,24 @@
     "appearance.preset.arctic": "Arctic",
     "appearance.preset.terminal": "Terminal",
     "appearance.preset.neon": "Neon",
+    "appearance.preset.sakura": "Sakura",
+    "appearance.preset.ocean": "Ocean",
+    "appearance.preset.copper": "Copper",
+    "appearance.preset.vapor": "Vapor",
+    "appearance.preset.monolith": "Monolith",
     "appearance.preset.applied": "Style preset applied",
     "appearance.bg.label": "Background Effects",
     "appearance.bg.hint": "Add an ambient background layer behind the interface.",
     "appearance.bg.none": "None",
     "appearance.bg.noise": "Noise Field",
+    "appearance.bg.aurora": "Aurora",
+    "appearance.bg.plasma": "Plasma",
+    "appearance.bg.rain": "Digital Rain",
+    "appearance.bg.stars": "Starfield",
+    "appearance.bg.warp": "Warp Tunnel",
     "appearance.bg.grid": "Dot Grid",
     "appearance.bg.mesh": "Gradient Mesh",
     "appearance.bg.scanlines": "Scanlines",
-    "appearance.bg.particles": "Particles",
     "appearance.bg.applied": "Background effect applied",
 
     "color_strip": {