Fix broken skater icon + add signup reassurance line (1.3.11)

- Regenerated the Lab skater icon (previous file was corrupted, showing a
  broken-image placeholder). Now a valid monochrome neon-red PNG.
- Signup welcome step: added a subtle, jargon-free reassurance line under
  "Create quick account" — "Takes 5 seconds · stays on this device ·
  nothing to remember" — to make quick signup feel effortless and safe.

Co-authored-by: shakespeare.diy <assistant@shakespeare.diy>

src/components/auth/SignupDialog.tsx

@@ -342,6 +342,11 @@ const SignupDialog: React.FC<SignupDialogProps> = ({ isOpen, onClose, onComplete
                   <Sparkles className='mr-2 h-4 w-4' />
                   Create quick account
                 </Button>
+                {/* Reassurance: effortless + safe, no jargon */}
+                <p className='flex items-center justify-center gap-1.5 text-[11px] text-gray-500'>
+                  <CheckCircle className='h-3 w-3 text-[#00ff00]/70' />
+                  Takes 5 seconds · stays on this device · nothing to remember
+                </p>
               </div>
 
               <p className='text-xs text-gray-500'>