fix: agent config search order — 1st arg > /etc/ > ~/.config/

The systemd service runs as root so /root is /root, but config is
written to /etc/servermanager/agent.conf. The agent now tries:
1. Path from command-line argument
2. /etc/servermanager/agent.conf (system mode)
3. $HOME/.config/servermanager/agent.conf (user mode)

Service ExecStart and cron job both pass the config path explicitly.

install/agent-install.sh

@@ -53,7 +53,14 @@ cat > "$AGENT_BIN" << 'AGENTSCRIPT'
 #!/bin/bash
 set -e
 
-CONFIG_FILE="${1:-$HOME/.config/servermanager/agent.conf}"
+# Config search order: 1st arg > /etc/servermanager/agent.conf > $HOME/.config/servermanager/agent.conf
+if [ -n "$1" ] && [ -f "$1" ]; then
+    CONFIG_FILE="$1"
+elif [ -f "/etc/servermanager/agent.conf" ]; then
+    CONFIG_FILE="/etc/servermanager/agent.conf"
+else
+    CONFIG_FILE="$HOME/.config/servermanager/agent.conf"
+fi
 
 load_config() {
     if [ -f "$CONFIG_FILE" ]; then
@@ -141,7 +148,7 @@ After=network-online.target
 Wants=network-online.target
 [Service]
 Type=simple
-ExecStart=/usr/local/bin/servermanager-agent
+ExecStart=/usr/local/bin/servermanager-agent /etc/servermanager/agent.conf
 Restart=always
 RestartSec=10
 [Install]
@@ -152,7 +159,7 @@ UNIT
     systemctl restart servermanager-agent 2>/dev/null || true
 else
     echo "  Using crontab (@reboot)..."
-    CRON_JOB="@reboot $AGENT_BIN > $CONFIG_DIR/agent.log 2>&1"
+    CRON_JOB="@reboot $AGENT_BIN $CONFIG_FILE > $CONFIG_DIR/agent.log 2>&1"
     (crontab -l 2>/dev/null | grep -v '_sm_agent\|servermanager-agent'; echo "$CRON_JOB") | crontab - 2>/dev/null || {
         echo "WARNING: Could not install crontab. Agent must be started manually."
         echo "  Run: $AGENT_BIN &"