Fix landing page: AGOSOS -> AGOS (remove duplicate OS suffix)

The heading was AGOS (gradient) + OS (plain span) = AGOSOS.
Remove the plain OS span — product name is just AGOS.

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Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

src/pages/Landing.tsx

@@ -503,7 +503,6 @@ export function Landing() {
               <div className="ne-Landing__splash-label">Welcome to</div>
               <h1 className="ne-Landing__splash-h1">
                 <GradientText>AGOS</GradientText>
-                <span className="ne-Landing__splash-h1-os">OS</span>
               </h1>
               <div className="ne-Landing__splash-sub">Agent Runtime Platform · CLI {version}</div>
             </div>