Separate tree nodes into independent panels, remove graph local search, UI improvements

- Split Sources tab: raw/raw_templates, processed/proc_templates each get own panel
- Split Targets tab: led-devices, led-targets, kc-targets, kc-patterns each get own panel
- Remove graph local search — search button and / key open global command palette
- Add graphNavigateToNode for command palette → graph node navigation
- Add tree group expand/collapse animation (max-height + opacity transition)
- Make tree group headers visually distinct (smaller, uppercase, left border on children)
- Make CardSection collapse opt-in via collapsible flag (disabled by default)
- Move filter textbox next to section title (remove margin-left: auto)
- Fix notification bell button vertical centering in test preview
- Fix clipboard copy on non-HTTPS with execCommand fallback
- Add overlay toggle button on picture-based CSS cards
- Add CSPT to graph add-entity picker and global search
- Update all cross-link navigation paths for new panel keys
- Add i18n keys for new tree groups and search groups (en/ru/zh)

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

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

@@ -417,8 +417,10 @@
   "section.collapse_all": "Collapse all sections",
   "streams.title": "Sources",
   "streams.description": "Sources define the capture pipeline. A raw source captures from a display using a capture template. A processed source applies postprocessing to another source. Assign sources to devices.",
-  "streams.group.raw": "Screen Capture",
-  "streams.group.processed": "Processed",
+  "streams.group.raw": "Sources",
+  "streams.group.raw_templates": "Engine Templates",
+  "streams.group.processed": "Sources",
+  "streams.group.proc_templates": "Filter Templates",
   "streams.group.css_processing": "Processing Templates",
   "streams.group.color_strip": "Color Strips",
   "streams.group.audio": "Audio",
@@ -1213,6 +1215,8 @@
   "audio_template.error.delete": "Failed to delete audio template",
   "streams.group.value": "Value Sources",
   "streams.group.sync": "Sync Clocks",
+  "tree.group.capture": "Screen Capture",
+  "tree.group.processing": "Processed",
   "tree.group.picture": "Picture",
   "tree.group.strip": "Color Strip",
   "tree.group.utility": "Utility",