Add graph editor filter, anchor-based positioning, and context docs

- Add name/kind/subtype filter bar with keyboard shortcut (F key)
- Filtered-out nodes get dimmed styling, nearly invisible on minimap
- Add anchor-based positioning for minimap and toolbar (remembers
  which corner element is closest to, maintains offset on resize)
- Fix minimap not movable after reload (_applyMinimapAnchor undefined)
- Fix ResizeObserver to use anchor system for both minimap and toolbar
- Add graph-editor.md context file and update frontend.md with graph sync notes
- Add filter i18n keys for en/ru/zh locales

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

server/src/wled_controller/static/js/app.js

@@ -160,7 +160,7 @@ import {
 // Layer 5.5: graph editor
 import {
     loadGraphEditor, openGraphSearch, closeGraphSearch,
-    toggleGraphLegend, toggleGraphMinimap,
+    toggleGraphLegend, toggleGraphMinimap, toggleGraphFilter,
     graphFitAll, graphZoomIn, graphZoomOut, graphRelayout,
     graphToggleFullscreen, graphAddEntity,
 } from './features/graph-editor.js';
@@ -469,6 +469,7 @@ Object.assign(window, {
     closeGraphSearch,
     toggleGraphLegend,
     toggleGraphMinimap,
+    toggleGraphFilter,
     graphFitAll,
     graphZoomIn,
     graphZoomOut,