Add visual graph editor for entity interconnections

SVG-based node graph with ELK.js autolayout showing all 13 entity types
and their relationships. Features include:

- Pan/zoom canvas with bounds clamping and dead-zone click detection
- Interactive minimap with viewport rectangle, click-to-pan, drag-to-move,
  and dual resize handles (bottom-left/bottom-right)
- Movable toolbar with drag handle and inline zoom percentage indicator
- Entity-type SVG icons from Lucide icon set with subtype-specific overrides
- Command palette search (/) with keyboard navigation and fly-to
- Node selection with upstream/downstream chain highlighting
- Double-click to zoom-to-card, edit/delete overlay on hover
- Legend panel, orphan node detection, running state indicators
- Full i18n support with languageChanged re-render
- Catmull-Rom-to-cubic bezier edge routing for smooth curves

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

server/src/wled_controller/static/js/features/tabs.js

@@ -70,6 +70,8 @@ export function switchTab(name, { updateHash = true, skipLoad = false } = {}) {
             if (typeof window.loadTargetsTab === 'function') window.loadTargetsTab();
         } else if (name === 'automations') {
             if (typeof window.loadAutomations === 'function') window.loadAutomations();
+        } else if (name === 'graph') {
+            if (typeof window.loadGraphEditor === 'function') window.loadGraphEditor();
         }
     }
 }