chore(rules): override fast-json-patch to 3.1.1 (Dependabot #103)

ajv-cli 5.0.0 is the latest release and still declares fast-json-patch ^2.0.0,
so neither Dependabot nor npm audit fix can move past CVE-2021-4279. An npm
override forces 3.1.1 into the lockfile; the 3.x API is backward compatible and
the validate command used in combine-rules.yml never touches the package.
Verified: npm ci from the lockfile plus all four ajv validate steps pass locally.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

rules/scripts/package.json

@@ -5,5 +5,8 @@
   "devDependencies": {
     "ajv-cli": "5.0.0",
     "ajv-formats": "3.0.1"
+  },
+  "overrides": {
+    "fast-json-patch": "3.1.1"
   }
 }