Enhance graph editor: fullscreen bg, add-entity focus, color picker fix, UI polish

- Move bg-anim canvas into graph container during fullscreen so dynamic background is visible
- Watch for new entity creation from graph add menu and auto-navigate to it after reload
- Position color picker at click coordinates instead of 0,0
- Replace test/preview play triangle with eye icon to distinguish from start/stop
- Always use port-aware bezier curves for edges instead of ELK routing
- Add fullscreen and add-entity buttons to toolbar with keyboard shortcuts (F11, +)
- Add confirmation dialog for relayout when manual positions exist
- Remove node body stroke, keep only color bar; add per-node color picker
- Clamp toolbar position on load to prevent off-screen drift
- Add graph tab to getting-started tutorial
- Add WASD/arrow spatial navigation, ESC reset, keyboard shortcuts

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

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

@@ -280,6 +280,7 @@
   "tour.dashboard": "Dashboard — live overview of running targets, automations, and device health at a glance.",
   "tour.targets": "Targets — add WLED devices, configure LED targets with capture settings and calibration.",
   "tour.sources": "Sources — manage capture templates, picture sources, audio sources, and color strips.",
+  "tour.graph": "Graph — visual overview of all entities and their connections. Drag ports to connect, right-click edges to disconnect.",
   "tour.automations": "Automations — automate scene switching with time, audio, or value conditions.",
   "tour.settings": "Settings — backup and restore configuration, manage auto-backups.",
   "tour.api": "API Docs — interactive REST API documentation powered by Swagger.",
@@ -1402,5 +1403,9 @@
   "graph.connection_updated": "Connection updated",
   "graph.connection_failed": "Failed to update connection",
   "graph.connection_removed": "Connection removed",
-  "graph.disconnect_failed": "Failed to disconnect"
+  "graph.disconnect_failed": "Failed to disconnect",
+  "graph.relayout_confirm": "Reset all manual node positions and re-layout the graph?",
+  "graph.fullscreen": "Toggle fullscreen",
+  "graph.add_entity": "Add entity",
+  "graph.color_picker": "Node color"
 }