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/en.json

@@ -677,6 +677,7 @@
   "pattern.description.hint": "Optional notes about where or how this pattern is used",
   "pattern.visual_editor.hint": "Click + buttons to add rectangles. Drag edges to resize, drag inside to move.",
   "pattern.rectangles.hint": "Fine-tune rectangle positions and sizes with exact coordinates (0.0 to 1.0)",
+  "overlay.toggle": "Toggle screen overlay",
   "overlay.button.show": "Show overlay visualization",
   "overlay.button.hide": "Hide overlay visualization",
   "overlay.started": "Overlay visualization started",
@@ -1344,6 +1345,7 @@
   "search.group.audio": "Audio Sources",
   "search.group.value": "Value Sources",
   "search.group.scenes": "Scene Presets",
+  "search.group.cspt": "Strip Processing Templates",
   "settings.backup.label": "Backup Configuration",
   "settings.backup.hint": "Download all configuration (devices, targets, streams, templates, automations) as a single JSON file.",
   "settings.backup.button": "Download Backup",