security: force lodash-es 4.18.0 for transitive dependencies (#242)

* security: force lodash-es 4.18.0 for transitive dependencies

PR #225 bumped the direct lodash-es dependency to 4.18.0, but
@anthropic-ai/sandbox-runtime still pulled lodash-es@4.17.23 via its
own ^4.17.23 range. The transitive copy was vulnerable to:

- HIGH: Code Injection via _.template (GHSA-r5fr-rjxr-66jc)
- MODERATE: Prototype Pollution via _.unset/_.omit (GHSA-f23m-r3pf-42rh)

Added overrides field in package.json to force all copies to 4.18.0.
bun audit now reports zero vulnerabilities.

* fix: use lodash-es 4.18.1 instead of deprecated 4.18.0

lodash-es 4.18.0 is explicitly deprecated by the maintainer with
the message "Bad release. Please use lodash-es@4.17.23 instead."
Updated both the direct dependency and the override to 4.18.1, which
is the latest non-deprecated release that patches the CVEs.

package.json

@@ -95,7 +95,7 @@
     "ignore": "7.0.5",
     "indent-string": "5.0.0",
     "jsonc-parser": "3.3.1",
-    "lodash-es": "4.18.0",
+    "lodash-es": "4.18.1",
     "lru-cache": "11.2.7",
     "marked": "15.0.12",
     "p-map": "7.0.4",
@@ -150,5 +150,8 @@
   "license": "SEE LICENSE FILE",
   "publishConfig": {
     "access": "public"
+  },
+  "overrides": {
+    "lodash-es": "4.18.1"
   }
 }