[Design] Updates some theme defaults

- Adds a couple variants to primary color
- Adds extra small option to edge insets metrics
- Adds Divider theme

lib/src/presentation/theme/_colors.dart

@@ -4,13 +4,17 @@ abstract class AppColors {
   static const Color white = Color(0xFFFFFFFF);
   static const Color background = Color(0xFFE6E6E6);
 
+  static const Color primaryLight = Color(0xFF8F96A3);
   static const Color primary = Color(0xFF000026);
   static const Color primaryDarker = Color(0xFF00001A);
 
   static const Color info = Color(0xFF0156B3);
   static const Color success = Color(0xFF29634B);
   static const Color warning = Color(0xFFF0B53C);
   static const Color danger = Color(0xFFB00020);
+
+  // Reduced Opacity (hover colors)
+  static const Color primary15 = Color(0x26000026);
 }
 
 const ColorScheme kColorScheme = ColorScheme.light(

lib/src/presentation/theme/_metrics.dart

@@ -21,6 +21,7 @@ abstract class AppBorderRadius {
 }
 
 abstract class AppEdgeInsets {
+  static const double xSmall = 4;
   static const double small = 8;
   static const double medium = 16;
   static const double large = 24;

lib/src/presentation/theme/theme.dart

@@ -8,6 +8,14 @@ final ThemeData kLightTheme = ThemeData(
   errorColor: AppColors.danger,
   tooltipTheme: tooltipTheme,
   navigationRailTheme: navigationRailTheme,
+  dividerTheme: dividerTheme,
+  hoverColor: AppColors.primary15,
+);
+
+const DividerThemeData dividerTheme = DividerThemeData(
+  color: AppColors.primaryLight,
+  space: 1.5,
+  thickness: 1.5,
 );
 
 final TooltipThemeData tooltipTheme = TooltipThemeData(
@@ -21,7 +29,7 @@ final TooltipThemeData tooltipTheme = TooltipThemeData(
 
 NavigationRailThemeData get navigationRailTheme {
   final Color selectedColor = kColorScheme.onPrimary;
-  final Color unselectedColor = kColorScheme.onPrimary.withOpacity(.4);
+  const Color unselectedColor = AppColors.primaryLight;
   const double iconSize = 32.0;
 
   return NavigationRailThemeData(
@@ -30,14 +38,14 @@ NavigationRailThemeData get navigationRailTheme {
       color: selectedColor,
       size: iconSize,
     ),
-    unselectedIconTheme: IconThemeData(
+    unselectedIconTheme: const IconThemeData(
       color: unselectedColor,
       size: iconSize,
     ),
     selectedLabelTextStyle: TextStyle(
       color: selectedColor,
     ),
-    unselectedLabelTextStyle: TextStyle(
+    unselectedLabelTextStyle: const TextStyle(
       color: unselectedColor,
     ),
   );