Add graph icon grid, search-to-graph nav, overlay on CSS cards, fix clipboard copy

- Convert graph editor add-entity menu to showTypePicker icon grid with SVG icons
- Add CSPT to graph add-entity picker and ALL_CACHES watcher
- Add graphNavigateToNode() — command palette navigates to graph node when graph tab active
- Add CSPT entities to global search palette results
- Add overlay toggle button on picture-based CSS cards (toggleCSSOverlay)
- Fix clipboard copy on non-HTTPS (LAN) with execCommand fallback for all copy functions
- Fix notification bell button vertical centering in test preview strip canvas
- Add overlay.toggle, search.group.cspt i18n keys (en/ru/zh)

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

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

@@ -626,6 +626,7 @@
   "pattern.description.hint": "关于此图案使用位置或方式的可选说明",
   "pattern.visual_editor.hint": "点击 + 按钮添加矩形。拖动边缘调整大小，拖动内部移动位置。",
   "pattern.rectangles.hint": "用精确坐标（0.0 到 1.0）微调矩形位置和大小",
+  "overlay.toggle": "切换屏幕叠加层",
   "overlay.button.show": "显示叠加层可视化",
   "overlay.button.hide": "隐藏叠加层可视化",
   "overlay.started": "叠加层可视化已启动",
@@ -1293,6 +1294,7 @@
   "search.group.audio": "音频源",
   "search.group.value": "值源",
   "search.group.scenes": "场景预设",
+  "search.group.cspt": "色带处理模板",
   "settings.backup.label": "备份配置",
   "settings.backup.hint": "将所有配置（设备、目标、流、模板、自动化）下载为单个 JSON 文件。",
   "settings.backup.button": "下载备份",