fix(security): scope ajv overrides to avoid top-level version conflict

Replacing global 'ajv: 8.18.0' override with scoped 'schema-utils@4'
override. The global override conflicted with the nested file-loader/
null-loader/url-loader overrides, causing npm to install ajv@6 at the
top level where ajv-keywords@5.x requires ajv@8 (ajv/dist/compile/codegen).

Now:
- schema-utils@3 + loaders → ajv@6.14.0 (safe minor bump)
- schema-utils@4 → ajv@8.18.0 (safe minor bump)
- top-level ajv unmodified (stays at 8.x for ajv-keywords@5)

docs/my-website/package.json

@@ -66,10 +66,12 @@
     "node-forge": ">=1.3.2",
     "mdast-util-to-hast": ">=13.2.1",
     "lodash-es": ">=4.17.23",
-    "ajv": "8.18.0",
     "schema-utils@3": {
       "ajv": "6.14.0"
     },
+    "schema-utils@4": {
+      "ajv": "8.18.0"
+    },
     "file-loader": {
       "ajv": "6.14.0"
     },