style: one spacing, title and skeleton language across the app

Icons inside buttons drop their manual margins in favour of the
button's built-in gap (two hundred call sites), form field stacks settle
on one spacing step, card titles on exactly two sizes, inline field
errors on one text size, and a dozen hand-rolled loading pulses move
onto the shared skeleton primitive while keeping their silhouettes. The
intake dialog wording joins the rest of the app on 'übersprungen', and
the UI guidelines now document the two deliberate footer and
touch-target systems.

src/app/loading.tsx

@@ -7,15 +7,16 @@
  * component — no client hooks, no data fetch. More specific segments (e.g.
  * `/insights`) provide their own skeleton and take precedence.
  */
+import { Skeleton } from "@/components/ui/skeleton";
 export default function RootLoading() {
   return (
     <div data-slot="dashboard-loading" className="space-y-6 p-4">
-      <div className="bg-muted h-7 w-44 animate-pulse rounded motion-reduce:animate-none" />
+      <Skeleton className="bg-muted h-7 w-44 rounded" />
       <div className="grid grid-cols-1 gap-4 sm:grid-cols-2 lg:grid-cols-3">
         {Array.from({ length: 6 }).map((_, i) => (
           <div key={i} className="bg-card rounded-xl border p-4">
-            <div className="bg-muted mb-3 h-4 w-24 animate-pulse rounded motion-reduce:animate-none" />
-            <div className="bg-muted/60 h-24 w-full animate-pulse rounded-lg motion-reduce:animate-none" />
+            <Skeleton className="bg-muted mb-3 h-4 w-24 rounded" />
+            <Skeleton className="h-24 w-full rounded-lg" />
           </div>
         ))}
       </div>