Heatmap solver is now a worker

- Android app now requests root (purpose still unknown)
- Android app starts on boot
- Frontend is now a PWA (purpose still unknown)

frontend/package.json

@@ -20,6 +20,7 @@
     "@angular/platform-browser": "~10.1.5",
     "@angular/platform-browser-dynamic": "~10.1.5",
     "@angular/router": "~10.1.5",
+    "@angular/service-worker": "~10.1.5",
     "@types/chart.js": "^2.9.27",
     "@types/mapbox-gl": "^1.12.5",
     "@types/moment": "^2.13.0",