refactor(ui): unify login page styling across web and desktop

- Use bordered icon with consistent size on both platforms
- Adjust font size to match icon proportions
- Simplify desktop tagline for cleaner presentation
- Streamline web login header to [icon] Sign In format

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/desktop/src/renderer/src/pages/login.tsx

@@ -33,15 +33,14 @@ export default function LoginPage() {
     <div className="flex h-screen flex-col items-center justify-center bg-background p-8 animate-in fade-in duration-300">
       <div className="w-full max-w-sm flex flex-col items-center text-center space-y-6">
         {/* Brand */}
-        <div className="flex items-center gap-2.5">
-          <MulticaIcon animate className="size-5 text-muted-foreground/70" />
-          <h1 className="text-2xl tracking-wide font-brand">Multica</h1>
+        <div className="flex items-center gap-2">
+          <MulticaIcon bordered animate size="md" />
+          <h1 className="text-lg tracking-wide font-brand">Multica</h1>
         </div>
 
         {/* Tagline */}
         <p className="text-sm text-muted-foreground leading-relaxed">
-          An AI assistant that gets things done — pulling data, running analysis,
-          and taking action. Talk to it like a team member.
+          An AI assistant that gets things done.
         </p>
 
         {/* Sign In */}

apps/web/app/login/login-form.tsx

@@ -202,14 +202,11 @@ export function LoginForm() {
       <div className="flex flex-col items-center text-center space-y-4">
         <div className="flex items-center gap-2">
           <MulticaIcon bordered noSpin size="md" />
-          <span className="text-base font-brand">Multica</span>
-        </div>
-        <div>
-          <h1 className="text-2xl font-semibold tracking-tight">Sign in</h1>
-          <p className="mt-1.5 text-sm text-muted-foreground">
-            Enter your email to continue
-          </p>
+          <h1 className="text-lg font-semibold tracking-tight">Sign In</h1>
         </div>
+        <p className="text-sm text-muted-foreground">
+          Enter your email to continue
+        </p>
       </div>
 
       {/* Error message */}