UID2-6699: Fix immutable and svgo HIGH vulnerabilities

Pin immutable to ^4.3.8 (fixes CVE-2026-29063, Prototype Pollution)
and svgo to ^3.3.3 (fixes CVE-2026-29074, Billion Laughs DoS) via
npm overrides in package.json.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: cYKatherine

package-lock.json

@@ -51,12 +51,14 @@
   },
   "overrides": {
     "body-parser@1": "1.20.3",
+    "immutable": "^4.3.8",
     "minimatch": "^10.2.3",
     "path-to-regexp@0": "0.1.12",
     "path-to-regexp@1": "1.9.0",
     "path-to-regexp@2": "8.0.0",
     "qs": "6.14.1",
-    "serialize-javascript": "^7.0.3"
+    "serialize-javascript": "^7.0.3",
+    "svgo": "^3.3.3"
   },
   "browserslist": {
     "production": [