fix(ui): size the page to the visible screen on phones

min-h-screen is 100vh, which mobile browsers measure without the address
bar, so short pages could be scrolled into empty space. 100dvh follows
the visible height.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/App.tsx

@@ -846,7 +846,7 @@ export const App: React.FC = () => {
 
   if (bootLoading) {
     return (
-      <div className="min-h-screen bg-canvas text-muted flex items-center justify-center text-xs font-sans">
+      <div className="min-h-[100dvh] bg-canvas text-muted flex items-center justify-center text-xs font-sans">
         Verbinde mit MindSift…
       </div>
     );
@@ -893,7 +893,7 @@ export const App: React.FC = () => {
   return (
     <div
       className={`bg-canvas text-main flex flex-col font-sans selection:bg-accent/30 ${
-        activeTab === 'workspace' ? 'h-[100dvh] overflow-hidden' : 'min-h-screen'
+        activeTab === 'workspace' ? 'h-[100dvh] overflow-hidden' : 'min-h-[100dvh]'
       }`}
     >
       {/* Top Header Bar: Floating on mobile, solid panel on desktop */}

frontend/src/features/auth/OAuthConsentView.tsx

@@ -56,7 +56,7 @@ export const OAuthConsentView: React.FC<OAuthConsentViewProps> = ({ user, instan
   const groups = SCOPE_GROUPS.filter(([group]) => SCOPES.some((sc) => sc.group === group && offered.includes(sc.id)));
 
   return (
-    <div className="min-h-screen bg-canvas text-main flex flex-col items-center justify-center p-4 font-sans">
+    <div className="min-h-[100dvh] bg-canvas text-main flex flex-col items-center justify-center p-4 font-sans">
       <div className="w-full max-w-md panel-surface shadow-panel overflow-hidden">
         <div className="p-4 bg-canvas border-b border-border flex items-center gap-2.5">
           <div className="w-7 h-7 bg-accent text-on-accent rounded-btn flex items-center justify-center">