Add visual IconSelect selectors for effect, palette, gradient, waveform dropdowns

Replace plain <select> dropdowns with rich visual selectors:
- Effect type: icon grid with descriptions
- Effect/audio palette: gradient strip previews from color data
- Gradient preset: gradient strip previews (13 presets)
- Audio visualization: icon grid with descriptions
- Notification effect: icon grid with descriptions
- Waveform (value source): inline SVG shape previews

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

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

@@ -840,8 +840,11 @@
   "color_strip.notification.effect": "效果：",
   "color_strip.notification.effect.hint": "通知触发时的视觉效果。闪烁线性衰减，脉冲平滑钟形曲线，扫描从左到右填充后衰减。",
   "color_strip.notification.effect.flash": "闪烁",
+  "color_strip.notification.effect.flash.desc": "瞬时点亮，线性衰减",
   "color_strip.notification.effect.pulse": "脉冲",
+  "color_strip.notification.effect.pulse.desc": "平滑钟形发光",
   "color_strip.notification.effect.sweep": "扫描",
+  "color_strip.notification.effect.sweep.desc": "从左到右填充然后消失",
   "color_strip.notification.duration": "持续时间（毫秒）：",
   "color_strip.notification.duration.hint": "通知效果播放的时长（毫秒）。",
   "color_strip.notification.default_color": "默认颜色：",
@@ -888,8 +891,11 @@
   "color_strip.audio.visualization": "可视化：",
   "color_strip.audio.visualization.hint": "音频数据如何渲染到 LED。",
   "color_strip.audio.viz.spectrum": "频谱分析",
+  "color_strip.audio.viz.spectrum.desc": "频率条分布在灯带上",
   "color_strip.audio.viz.beat_pulse": "节拍脉冲",
+  "color_strip.audio.viz.beat_pulse.desc": "所有LED随节拍脉动",
   "color_strip.audio.viz.vu_meter": "VU 表",
+  "color_strip.audio.viz.vu_meter.desc": "音量填充灯带",
   "color_strip.audio.source": "音频源：",
   "color_strip.audio.source.hint": "此可视化的音频源。可以是多声道（设备）或单声道（单通道）源。在源标签页中创建和管理音频源。",
   "color_strip.audio.sensitivity": "灵敏度：",