chore(oss/js): fix ToolRuntime references in docs (#1338)

Fixes langchain-ai/langchainjs#9318

Author: hntrl

src/oss/langchain/context-engineering.mdx

@@ -691,7 +691,7 @@ import { tool } from "@langchain/core/tools";
 import { z } from "zod";
 
 const searchOrders = tool(
-  async ({ userId, status, limit = 10 }) => {
+  async ({ userId, status, limit }) => {
     // Implementation here
   },
   {
@@ -1612,11 +1612,10 @@ Most real-world tools need more than just the LLM's parameters. They need user I
 
     ```typescript
     import * as z from "zod";
-    import { tool } from "@langchain/core/tools";
-    import { createAgent } from "langchain";
+    import { createAgent, tool, type ToolRuntime } from "langchain";
 
     const checkAuthentication = tool(
-      async (_, { runtime }) => {
+      async (_, runtime: ToolRuntime) => {
         // Read from State: check current auth status
         const currentState = runtime.state;
         const isAuthenticated = currentState.authenticated || false;
@@ -1683,15 +1682,14 @@ Most real-world tools need more than just the LLM's parameters. They need user I
 
     ```typescript
     import * as z from "zod";
-    import { tool } from "@langchain/core/tools";
-    import { createAgent } from "langchain";
+    import { createAgent, tool, type ToolRuntime } from "langchain";
 
     const contextSchema = z.object({
       userId: z.string(),
     });
 
     const getPreference = tool(
-      async ({ preferenceKey }, { runtime }) => {
+      async ({ preferenceKey }, runtime: ToolRuntime) => {
         const userId = runtime.context.userId;
 
         // Read from Store: get existing preferences
@@ -1781,7 +1779,7 @@ Most real-world tools need more than just the LLM's parameters. They need user I
     });
 
     const fetchUserData = tool(
-      async ({ query }, { runtime }) => {
+      async ({ query }, runtime: ToolRuntime<any, typeof contextSchema>) => {
         // Read from Runtime Context: get API key and DB connection
         const { userId, apiKey, dbConnection } = runtime.context;
 
@@ -1856,7 +1854,7 @@ and update the memory of the agent to make important context available to future
     import { Command } from "@langchain/langgraph";
 
     const authenticateUser = tool(
-      async ({ password }, { runtime }) => {
+      async ({ password }) => {
         // Perform authentication
         if (password === "correct") {
           // Write to State: mark as authenticated using Command
@@ -1929,15 +1927,10 @@ and update the memory of the agent to make important context available to future
 
     ```typescript
     import * as z from "zod";
-    import { tool } from "@langchain/core/tools";
-    import { createAgent } from "langchain";
-
-    const contextSchema = z.object({
-      userId: z.string(),
-    });
+    import { createAgent, tool, type ToolRuntime } from "langchain";
 
     const savePreference = tool(
-      async ({ preferenceKey, preferenceValue }, { runtime }) => {
+      async ({ preferenceKey, preferenceValue }, runtime: ToolRuntime<any, typeof contextSchema>) => {
         const userId = runtime.context.userId;
 
         // Read existing preferences