Replace bare — and generic None in selectors with descriptive None (reason) labels

All optional entity selectors now use the format "None (description)" with
i18n keys instead of hardcoded "—" or bare "None". Added common.none_no_cspt,
common.none_no_input, common.none_own_speed keys to all 3 locales. Updated
frontend context with the convention.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

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

@@ -410,6 +410,9 @@
   "common.edit": "编辑",
   "common.clone": "克隆",
   "common.none": "无",
+  "common.none_no_cspt": "无（无处理模板）",
+  "common.none_no_input": "无（无输入源）",
+  "common.none_own_speed": "无（使用自身速度）",
   "palette.search": "搜索…",
   "section.filter.placeholder": "筛选...",
   "section.filter.reset": "清除筛选",
@@ -803,7 +806,7 @@
   "automations.scene": "场景：",
   "automations.scene.hint": "条件满足时激活的场景预设",
   "automations.scene.search_placeholder": "搜索场景...",
-  "automations.scene.none_selected": "无场景",
+  "automations.scene.none_selected": "无（无场景）",
   "automations.scene.none_available": "没有可用的场景",
   "automations.deactivation_mode": "停用方式：",
   "automations.deactivation_mode.hint": "条件不再满足时的行为",
@@ -1097,7 +1100,7 @@
   "color_strip.composite.blend_mode.screen.desc": "提亮，正片叠底的反转",
   "color_strip.composite.opacity": "不透明度",
   "color_strip.composite.brightness": "亮度",
-  "color_strip.composite.brightness.none": "— 无 —",
+  "color_strip.composite.brightness.none": "无（全亮度）",
   "color_strip.composite.processing": "处理",
   "color_strip.composite.enabled": "启用",
   "color_strip.composite.error.min_layers": "至少需要 1 个图层",