redesign: complete UI overhaul for 54 nodes and 26 projects

- Replace D3 force graph with categorized grid layout for topology
  (54 nodes organized by type: infrastructure, servers, PCs, etc.)
- Replace individual task cards with project summary cards
  (progress bars and stage chips instead of 1700+ task cards)
- Compact node cards with status-colored backgrounds
- Better calendar empty state with centered icon
- Refined dark theme with more color depth
- Remove D3 dependency (no longer needed)
- Fix text sizes for 4K TV readability at distance

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

frontend/package.json

@@ -18,8 +18,6 @@
     "vite": "^7.3.1"
   },
   "dependencies": {
-    "@types/d3": "^7.4.3",
-    "d3": "^7.9.0",
     "framer-motion": "^12.34.0",
     "react": "^19.2.4",
     "react-dom": "^19.2.4"