Unify the dashboard experience and retire the multi-theme engine so onboarding and day-to-day invoicing feel consistent and easier to maintain.

Shared layout, tabs, and sidebar timer; user onboarding and registration polish; settings danger zone and data export; chart and tRPC perf fixes; migrations for onboarding and dropped appearance columns.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/components/ui/tabs.tsx

@@ -11,7 +11,7 @@ const Tabs = React.forwardRef<
 >(({ className, ...props }, ref) => (
   <TabsPrimitive.Root
     ref={ref}
-    className={cn("flex flex-col gap-1", className)}
+    className={cn("flex flex-col gap-2", className)}
     {...props}
   />
 ));
@@ -54,7 +54,7 @@ const TabsContent = React.forwardRef<
   <TabsPrimitive.Content
     ref={ref}
     className={cn(
-      "ring-offset-background focus-visible:ring-ring mt-1 focus-visible:ring-2 focus-visible:ring-offset-2 focus-visible:outline-none",
+      "ring-offset-background focus-visible:ring-ring focus-visible:ring-2 focus-visible:ring-offset-2 focus-visible:outline-none",
       className,
     )}
     {...props}