feat(zod-v4): support zod v3 and v4 simultaneously

Author: dclark27

README.md

@@ -58,7 +58,7 @@ Let's create a simple MCP server that exposes a calculator tool and some data. S
 import { McpServer, ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 import express from 'express';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 // Create an MCP server
 const server = new McpServer({
@@ -477,7 +477,7 @@ MCP servers can request LLM completions from connected clients that support samp
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 import express from 'express';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 const mcpServer = new McpServer({
     name: 'tools-with-sample-server',
@@ -561,7 +561,7 @@ For most use cases where session management isn't needed:
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 import express from 'express';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 const app = express();
 app.use(express.json());
@@ -796,7 +796,7 @@ A simple server demonstrating resources, tools, and prompts:
 
 ```typescript
 import { McpServer, ResourceTemplate } from '@modelcontextprotocol/sdk/server/mcp.js';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 const server = new McpServer({
     name: 'echo-server',
@@ -866,7 +866,7 @@ A more complex example showing database integration:
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import sqlite3 from 'sqlite3';
 import { promisify } from 'util';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 const server = new McpServer({
     name: 'sqlite-explorer',
@@ -961,7 +961,7 @@ If you want to offer an initial set of tools/prompts/resources, but later add ad
 import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
 import { StreamableHTTPServerTransport } from '@modelcontextprotocol/sdk/server/streamableHttp.js';
 import express from 'express';
-import { z } from 'zod';
+import * as z from 'zod/v4'; // or import * as z from 'zod/v3';
 
 const server = new McpServer({
     name: 'Dynamic Example',