fix(install): install gateway daemon service for fresh installs

- Add install_gateway_daemon_if_needed() function
- Call daemon install and daemon start for new installs
- Skip for upgrades (existing behavior)
- Fixes #48272 where gateway was not installed

Root cause:
The install script only refreshed the gateway service if it was already
loaded, but never installed it for fresh installs.

Fix:
1. Check if gateway daemon is already installed
2. If not, run 'openclaw daemon install'
3. Then run 'openclaw daemon start'
4. Probe the daemon to verify it's running

scripts/install.sh

@@ -2243,6 +2243,45 @@ refresh_gateway_service_if_loaded() {
     run_quiet_step "Probing gateway service" "$claw" gateway status --deep || true
 }
 
+install_gateway_daemon_if_needed() {
+    if [[ "${SKIP_GATEWAY_DAEMON:-0}" == "1" ]]; then
+        ui_info "Skipping gateway daemon installation (SKIP_GATEWAY_DAEMON=1)"
+        return 0
+    fi
+    
+    local claw="${OPENCLAW_BIN:-}"
+    if [[ -z "$claw" ]]; then
+        claw="$(resolve_openclaw_bin || true)"
+    fi
+    if [[ -z "$claw" ]]; then
+        ui_info "Skipping gateway daemon install (openclaw not on PATH yet)"
+        return 0
+    fi
+
+    if is_gateway_daemon_loaded "$claw"; then
+        ui_info "Gateway daemon already installed; skipping install"
+        return 0
+    fi
+
+    ui_info "Installing gateway daemon service"
+    if run_quiet_step "Installing gateway daemon" "$claw" daemon install; then
+        ui_success "Gateway daemon service installed"
+    else
+        ui_warn "Gateway daemon install failed; user can run 'openclaw daemon install' manually"
+        return 0
+    fi
+
+    if run_quiet_step "Starting gateway daemon" "$claw" daemon start; then
+        ui_success "Gateway daemon service started"
+    else
+        ui_warn "Gateway daemon start failed; user can run 'openclaw daemon start' manually"
+        return 0
+    fi
+
+    sleep 2
+    run_quiet_step "Probing gateway daemon" "$claw" daemon status --deep || true
+}
+
 verify_installation() {
     if [[ "${VERIFY_INSTALL}" != "1" ]]; then
         return 0
@@ -2400,6 +2439,11 @@ main() {
         fi
     fi
 
+    # Install gateway daemon for fresh installs (not upgrades)
+    if [[ "$is_upgrade" != "true" ]]; then
+        install_gateway_daemon_if_needed
+    fi
+
     refresh_gateway_service_if_loaded
 
     # Step 6: Run doctor for migrations on upgrades and git installs