feat(demo): funnel server-less users to the OpenCode Connect waitlist (#127)

The demo's only exit CTA was 'Connect your own server' — useless for the
majority of installers who have no server (the exact churn/retention segment).
Adds a secondary CTA pointing them to the OpenCode Connect (hosted, no-setup)
waitlist, which is the monetization funnel per the founder strategy. Additive,
reuses the existing waitlist on /connection/add and the demo's exit-tracking;
i18n en+zh in parity.


Claude-Session: https://claude.ai/code/session_01T12AhSnQVrSxNnvwfCx2z6

Co-authored-by: engineer <engineer@macbookpro.lan>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

app/demo.tsx

@@ -85,6 +85,13 @@ export default function DemoScreen() {
             >
               <Text style={s.connectButtonText}>{t("demo.connectButton")}</Text>
             </TouchableOpacity>
+            <TouchableOpacity
+              style={s.hostedCtaLink}
+              onPress={handleConnectPress}
+              testID="demo-hosted-cta"
+            >
+              <Text style={s.hostedCtaLinkText}>{t("demo.hostedCtaLink")}</Text>
+            </TouchableOpacity>
             <TouchableOpacity
               style={s.setupGuideLink}
               onPress={() => Linking.openURL(SETUP_GUIDE_URL)}
@@ -140,6 +147,8 @@ const s = StyleSheet.create({
     alignItems: "center",
   },
   connectButtonText: { color: "#ffffff", fontWeight: "600", fontSize: 15 },
+  hostedCtaLink: { marginTop: 14 },
+  hostedCtaLinkText: { fontSize: 14, fontWeight: "600", color: "#8b5cf6", textAlign: "center" },
   setupGuideLink: { marginTop: 14 },
   setupGuideLinkText: { fontSize: 14, fontWeight: "600", color: "#6366f1" },
 })