feat: add subnet-based CORS validation support for VPN/Tailscale origins

- Add ipaddress module for subnet parsing (10.0.0.0/24 format)
- Implement subnet validation in CORS middleware
- Separate individual IPs from subnet definitions in EXTRA_ALLOWED_ORIGINS
- Custom SubnetAwareCORSMiddleware for dynamic origin validation
- Support both exact IP matches and subnet ranges
- Backward compatible with existing ALLOWED_ORIGINS list

frontend/package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "inventory-pwa",
-  "version": "0.1.0",
+  "version": "0.2.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "inventory-pwa",
-      "version": "0.1.0",
+      "version": "0.2.0",
       "dependencies": {
         "axios": "^1.15.0",
         "clsx": "^2.1.1",