multiple updates

- colour theme implemented. ThemeService based global switching for future light detection triggers
- test flipflop service for various fun
- navigator widget class with state switching

pi/ui/lib/widgets/stat_box.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 
+import '../theme/app_theme.dart';
+
 /// A labeled stat display box for the dashboard
 class StatBox extends StatelessWidget {
   final String label;
@@ -9,18 +11,22 @@ class StatBox extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final theme = AppTheme.of(context);
+
     return Column(
       children: [
         Text(
           value,
           style: Theme.of(context).textTheme.headlineMedium?.copyWith(
-            color: Colors.white,
+            fontSize: 100,
+            color: theme.foreground,
           ),
         ),
         Text(
           label,
           style: Theme.of(context).textTheme.bodySmall?.copyWith(
-            color: Colors.grey,
+            fontSize: 80,
+            color: theme.subdued,
             letterSpacing: 1,
           ),
         ),