fix: UserMenu dropdown unclickable + game cards behind BottomNav

- .nav z-index: 10 so dropdown escapes stacking context above .main
- Dashboard .main bottom padding 24px -> 80px for BottomNav clearance
- Chat Home button reduced to match mobile sizing (36px / 0.82rem)

Author: Partha-dev01

app/globals.css

@@ -174,6 +174,8 @@ body {
   background: var(--nav-bg);
   backdrop-filter: blur(12px);
   border-bottom: 2px solid var(--border);
+  position: relative;
+  z-index: 10;
   transition:
     background 400ms var(--ease),
     border-color 400ms var(--ease);

app/kid-dashboard/chat/page.tsx

@@ -223,7 +223,7 @@ export default function ChatPage() {
         <NavLogo />
         <div style={{ display: "flex", alignItems: "center", gap: 10 }}>
           <ThemeToggle theme={theme} onToggle={() => setTheme((t) => (t === "light" ? "dark" : "light"))} />
-          <Link href="/kid-dashboard" className="btn btn-outline" style={{ minHeight: 40, padding: "8px 14px", fontSize: "0.85rem" }}>
+          <Link href="/kid-dashboard" className="btn btn-outline" style={{ minHeight: 36, padding: "6px 12px", fontSize: "0.82rem" }}>
             Home
           </Link>
           <UserMenu />

app/kid-dashboard/page.tsx

@@ -122,7 +122,7 @@ export default function KidDashboardPage() {
         </div>
       </nav>
 
-      <div className="main fade fade-1" style={{ maxWidth: 900, padding: "24px 20px 24px" }}>
+      <div className="main fade fade-1" style={{ maxWidth: 900, padding: "24px 20px 80px" }}>
         {/* Welcome */}
         <div className="fade fade-1" style={{ marginBottom: 20 }}>
           <h1