chore(langgraph): make Zod a peer dependency

.changeset/bumpy-candies-bake.md

@@ -0,0 +1,5 @@
+---
+"@langchain/langgraph": major
+---
+
+Make Zod a peer dependency of @langchain/langgraph

libs/langgraph/package.json

@@ -34,12 +34,12 @@
   "dependencies": {
     "@langchain/langgraph-checkpoint": "^0.1.0",
     "@langchain/langgraph-sdk": "~0.0.111",
-    "uuid": "^10.0.0",
-    "zod": "^3.25.32"
+    "uuid": "^10.0.0"
   },
   "peerDependencies": {
     "@langchain/core": ">=0.3.58 < 0.4.0",
-    "zod-to-json-schema": "^3.x"
+    "zod-to-json-schema": "^3.x",
+    "zod": "^3.25.32 || ^4.1.0"
   },
   "peerDependenciesMeta": {
     "zod-to-json-schema": {
@@ -187,4 +187,4 @@
     "zod/schema.d.ts",
     "zod/schema.d.cts"
   ]
-}
+}