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/main.dart

@@ -1,6 +1,8 @@
 import 'package:flutter/material.dart';
 
 import 'app_root.dart';
+import 'theme/app_colors.dart';
+import 'theme/app_theme.dart';
 
 void main() {
   runApp(const SmartSerowApp());
@@ -11,18 +13,20 @@ class SmartSerowApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Smart Serow',
-      debugShowCheckedModeBanner: false,
-      theme: ThemeData(
-        colorScheme: ColorScheme.fromSeed(
-          seedColor: Colors.teal,
-          brightness: Brightness.dark,
+    return AppThemeProvider(
+      child: MaterialApp(
+        title: 'Smart Serow',
+        debugShowCheckedModeBanner: false,
+        theme: ThemeData(
+          colorScheme: ColorScheme.fromSeed(
+            seedColor: AppColors.darkSubdued,
+            brightness: Brightness.dark,
+          ),
+          useMaterial3: true,
+          fontFamily: 'DIN1451',
         ),
-        useMaterial3: true,
-        fontFamily: 'DIN1451',
+        home: const AppRoot(),
       ),
-      home: const AppRoot(),
     );
   }
 }