Clean up examples (#182)

* Centralize example server transport logic in shared utils

Move stdio/HTTP transport handling into `server-utils.ts` so example
servers only need to call `startServer(createServer)`. Switch HTTP
transport to stateless mode and remove legacy SSE endpoints.

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Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Make example servers self-contained with local server-utils

Copy `server-utils.ts` into each example's `src/` directory so examples
can be used standalone without the shared directory. Updates imports
from `"../shared/server-utils.js"` to `"./src/server-utils.js"`.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

* Add `integration-server` example for E2E testing

Add dedicated `integration-server` example (duplicated from
`basic-server-react`) to preserve E2E testing capabilities while
allowing `basic-server-react` to be simplified as a minimal example.

Changes:
- Add `examples/integration-server` exercising SDK communication APIs
- Update E2E tests to use `integration-server` instead of
  `basic-server-react` and `basic-server-vanillajs`
- Use server name labels instead of indices for more robust test
  selection
- Remove `basic-react.png` and `basic-vanillajs.png` golden snapshots

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

* Simplify `basic-server-*` examples

- Clarify comments
- Return plain text from `get-time` tool instead of JSON
- Remove simulated cleanup delay from `onteardown`

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

examples/cohort-heatmap-server/server.ts

@@ -1,5 +1,4 @@
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
-import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
 import type { ReadResourceResult } from "@modelcontextprotocol/sdk/types.js";
 import fs from "node:fs/promises";
 import path from "node:path";
@@ -10,7 +9,7 @@ import {
   registerAppResource,
   registerAppTool,
 } from "@modelcontextprotocol/ext-apps/server";
-import { startServer } from "../shared/server-utils.js";
+import { startServer } from "./src/server-utils.js";
 
 const DIST_DIR = path.join(import.meta.dirname, "dist");
 
@@ -211,16 +210,4 @@ function createServer(): McpServer {
   return server;
 }
 
-async function main() {
-  if (process.argv.includes("--stdio")) {
-    await createServer().connect(new StdioServerTransport());
-  } else {
-    const port = parseInt(process.env.PORT ?? "3104", 10);
-    await startServer(createServer, { port, name: "Cohort Heatmap Server" });
-  }
-}
-
-main().catch((e) => {
-  console.error(e);
-  process.exit(1);
-});
+startServer(createServer);