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/app.js

@@ -157,6 +157,13 @@ import {
     updateCalibrationLine, resetCalibrationView,
 } from './features/advanced-calibration.js';
 
+// Layer 5.5: graph editor
+import {
+    loadGraphEditor, openGraphSearch, closeGraphSearch,
+    toggleGraphLegend, toggleGraphMinimap,
+    graphFitAll, graphZoomIn, graphZoomOut, graphRelayout,
+} from './features/graph-editor.js';
+
 // Layer 6: tabs, navigation, command palette, settings
 import { switchTab, initTabs, startAutoRefresh, handlePopState } from './features/tabs.js';
 import { navigateToCard } from './core/navigation.js';
@@ -455,6 +462,17 @@ Object.assign(window, {
     updateCalibrationLine,
     resetCalibrationView,
 
+    // graph editor
+    loadGraphEditor,
+    openGraphSearch,
+    closeGraphSearch,
+    toggleGraphLegend,
+    toggleGraphMinimap,
+    graphFitAll,
+    graphZoomIn,
+    graphZoomOut,
+    graphRelayout,
+
     // tabs / navigation / command palette
     switchTab,
     startAutoRefresh,
@@ -488,7 +506,7 @@ document.addEventListener('keydown', (e) => {
 
     // Tab shortcuts: Ctrl+1..4 (skip when typing in inputs)
     if (!inInput && e.ctrlKey && !e.altKey && !e.shiftKey && !e.metaKey) {
-        const tabMap = { '1': 'dashboard', '2': 'automations', '3': 'targets', '4': 'streams' };
+        const tabMap = { '1': 'dashboard', '2': 'automations', '3': 'targets', '4': 'streams', '5': 'graph' };
         const tab = tabMap[e.key];
         if (tab) {
             e.preventDefault();