feat: publish example servers to npm (#184)

* feat: publish example servers to npm

Make example MCP App servers publishable to npm under the
@modelcontextprotocol scope:

- server-basic-react
- server-basic-vanillajs
- server-budget-allocator
- server-cohort-heatmap
- server-customer-segmentation
- server-scenario-modeler
- server-system-monitor
- server-threejs
- server-wiki-explorer

Changes:
- Remove `private: true` from example package.json files
- Add proper npm metadata (description, repository, license, files)
- Update ext-apps dependency from relative to ^0.2.2
- Copy server-utils.ts into each package for standalone use
- Add publish-examples job to npm-publish.yml workflow

The examples will be published automatically when a GitHub release
is created, after the main SDK package is published.

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

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

* feat: publish examples with pkg-pr-new for PR testing

* feat: export createServer from example servers

* style: format integration-server/server.ts

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

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

* fix: update e2e snapshots for basic-server examples

Update golden screenshots for basic-react and basic-vanillajs after
the tool output was simplified from JSON to plain text in #182.

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

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

* merge

* refactor: update sheet-music-server and video-resource-server to new publishing pattern

- Move server-utils.ts from src/ to root level
- Add npm publishing metadata (scoped name, repository, license, files)
- Change ext-apps dependency from local to versioned ^0.2.2
- Update server.ts to handle stdio mode inline

* update package-lock

* fix: update package-lock.json for renamed server packages

* feat: add NASA public domain video to video-resource-server

Added 'nasa-earth' option - NASA ISS Earth observations (6.4MB).
Source: archive.org/details/NASA-Ultra-High-Definition (public domain)

* fix: add default videoId for video-resource-server

* fix: use existing bunny-1mb as default video, remove nasa-earth

* refactor: update new framework examples to publishing pattern

Add publishing metadata for:
- @modelcontextprotocol/server-basic-preact
- @modelcontextprotocol/server-basic-solid
- @modelcontextprotocol/server-basic-svelte
- @modelcontextprotocol/server-basic-vue

Changes:
- Move server-utils.ts from src/ to root
- Add npm publishing metadata
- Update ext-apps dep to versioned ^0.2.2
- Add stdio mode support in main()

* fix: add missing @rollup/rollup-win32-arm64-msvc to optionalDependencies

This fixes the Windows ARM64 CI build failure caused by npm's optional
dependency bug. The package.json was missing this platform-specific
rollup binding.

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Olivier Chafik <ochafik@anthropic.com>

examples/basic-server-react/server-utils.ts

@@ -0,0 +1,68 @@
+/**
+ * Shared utilities for running MCP servers with Streamable HTTP transport.
+ */
+
+import { createMcpExpressApp } from "@modelcontextprotocol/sdk/server/express.js";
+import type { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
+import { StreamableHTTPServerTransport } from "@modelcontextprotocol/sdk/server/streamableHttp.js";
+import cors from "cors";
+import type { Request, Response } from "express";
+
+export interface ServerOptions {
+  port: number;
+  name?: string;
+}
+
+/**
+ * Starts an MCP server with Streamable HTTP transport in stateless mode.
+ *
+ * @param createServer - Factory function that creates a new McpServer instance per request.
+ * @param options - Server configuration options.
+ */
+export async function startServer(
+  createServer: () => McpServer,
+  options: ServerOptions,
+): Promise<void> {
+  const { port, name = "MCP Server" } = options;
+
+  const app = createMcpExpressApp({ host: "0.0.0.0" });
+  app.use(cors());
+
+  app.all("/mcp", async (req: Request, res: Response) => {
+    const server = createServer();
+    const transport = new StreamableHTTPServerTransport({
+      sessionIdGenerator: undefined,
+    });
+
+    res.on("close", () => {
+      transport.close().catch(() => {});
+      server.close().catch(() => {});
+    });
+
+    try {
+      await server.connect(transport);
+      await transport.handleRequest(req, res, req.body);
+    } catch (error) {
+      console.error("MCP error:", error);
+      if (!res.headersSent) {
+        res.status(500).json({
+          jsonrpc: "2.0",
+          error: { code: -32603, message: "Internal server error" },
+          id: null,
+        });
+      }
+    }
+  });
+
+  const httpServer = app.listen(port, () => {
+    console.log(`${name} listening on http://localhost:${port}/mcp`);
+  });
+
+  const shutdown = () => {
+    console.log("\nShutting down...");
+    httpServer.close(() => process.exit(0));
+  };
+
+  process.on("SIGINT", shutdown);
+  process.on("SIGTERM", shutdown);
+}