treewide: use dot shorthands where possible

Now this feature is stable, we should use it. I might have missed some usecases, but these can be added in future commits.

lib/helpers/extensions/scheme_to_theme.dart

@@ -1,16 +1,16 @@
 import "package:flutter/material.dart";
 
 extension SchemeToTheme on ColorScheme {
-  ThemeData get theme => ThemeData.from(colorScheme: this).copyWith(
-    cardTheme: CardThemeData(color: primaryContainer),
+  ThemeData get theme => .from(colorScheme: this).copyWith(
+    cardTheme: .new(color: primaryContainer),
+    popupMenuTheme: .new(
+      shape: RoundedRectangleBorder(borderRadius: .circular(16)),
+      color: surfaceContainerHigh,
+    ),
     appBarTheme: AppBarTheme(
       titleSpacing: 0,
       backgroundColor: surfaceContainerLow,
     ),
-    popupMenuTheme: PopupMenuThemeData(
-      shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(16)),
-      color: surfaceContainerHigh,
-    ),
     textTheme: ThemeData(
       fontFamilyFallback: ["sans", "emoji"],
       brightness: brightness,