feat: add upgrade and update scripts for docker + submodule workflow

upgrade.sh

@@ -0,0 +1,42 @@
+#!/bin/bash
+set -e
+
+echo "======================================"
+echo "  Upgrading NexusGuard SD-WAN Suite  "
+echo "======================================"
+
+# Step 1: Docker down
+echo "[+] Stopping Docker containers..."
+docker-compose down --remove-orphans
+echo "[+] Docker containers stopped."
+
+# Step 2: Git pull main repo
+echo "[+] Pulling latest main repo..."
+git pull
+
+# Step 3: Update submodules
+echo "[+] Updating submodules..."
+git submodule update --init --recursive
+
+# Step 4: Submodule checkout — pull latest main on each
+for sub in apps/server-core apps/device-agent apps/dashboard-ui; do
+    if [ -d "$sub" ]; then
+        echo "[+] Updating $sub..."
+        cd "$sub"
+        git checkout main 2>/dev/null || git checkout master 2>/dev/null || true
+        git pull
+        cd - > /dev/null
+    fi
+done
+
+# Step 5: Re-check superproject submodule pointers
+git submodule update --remote --merge 2>/dev/null || true
+
+# Step 6: Docker up
+echo "[+] Starting Docker containers..."
+docker-compose up -d
+
+echo "======================================"
+echo "  NexusGuard upgrade complete!       "
+echo "  API Port : 8080                    "
+echo "======================================"