Unify process picker, improve notification CSS editor, remove notification led_count

- Extract shared process picker module (core/process-picker.js) used by
  both automation conditions and notification CSS app filter
- Remove led_count property from notification CSS source (backend + frontend)
- Replace comma-separated app filter with newline-separated textarea + browse
- Inline color cycle add button (+) into the color row
- Fix notification app color layout to horizontal rows

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

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

@@ -826,8 +826,8 @@
   "color_strip.notification.filter_mode.whitelist": "白名单",
   "color_strip.notification.filter_mode.blacklist": "黑名单",
   "color_strip.notification.filter_list": "应用列表：",
-  "color_strip.notification.filter_list.hint": "以逗号分隔的应用名称。",
-  "color_strip.notification.filter_list.placeholder": "Discord, Slack, Telegram",
+  "color_strip.notification.filter_list.hint": "每行一个应用名称。使用「浏览」从运行中的进程中选择。",
+  "color_strip.notification.filter_list.placeholder": "Discord\nSlack\nTelegram",
   "color_strip.notification.app_colors": "应用颜色",
   "color_strip.notification.app_colors.label": "颜色映射：",
   "color_strip.notification.app_colors.hint": "每个应用的自定义通知颜色。每行将一个应用名称映射到特定颜色。",