sync: interactive map canvas from private repo

- React Flow replaces custom SVG map (node dragging, edge creation, SSE sync)
- Redesigned QuickAddInput and EdgeExplanationModal (match SearchModal design)
- Selection highlighting with edge/node dimming
- Added tabBar prop to BasePaneProps and PaneHeaderProps
- Removed stale activeDelegations prop from QuickAddInput callers

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

package.json

@@ -30,6 +30,7 @@
     "@radix-ui/react-dropdown-menu": "^2.1.1",
     "@radix-ui/react-label": "^2.1.0",
     "@radix-ui/react-slot": "^1.1.0",
+    "@xyflow/react": "^12.10.0",
     "ai": "^6.0.27",
     "better-sqlite3": "^12.2.0",
     "cheerio": "^1.1.2",