feat(mcp): add stdio + streamable HTTP transports, CLI, and smoke test

- connectStdio(server): wires the MCP server to StdioServerTransport.
- connectHttp(server, port): wires the MCP server to
  StreamableHTTPServerTransport over node:http. Returns a handle with
  port and close().
- bin/pascal-mcp.ts: CLI entrypoint with --stdio (default), --http,
  --port, --scene, --help, --version. Loads node-shims before any
  core import. Logs to stderr (stdio transport uses stdout for
  JSON-RPC).
- scripts/smoke.ts: end-to-end smoke — spawns the stdio bin, connects
  as an MCP Client, exercises get_scene, create_level, validate_scene,
  undo.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/mcp/src/transports/http.test.ts

@@ -0,0 +1,64 @@
+import { afterEach, beforeEach, expect, test } from 'bun:test'
+import { Client } from '@modelcontextprotocol/sdk/client/index.js'
+import { StreamableHTTPClientTransport } from '@modelcontextprotocol/sdk/client/streamableHttp.js'
+import type { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js'
+import { SceneBridge } from '../bridge/scene-bridge'
+import { createPascalMcpServer } from '../server'
+import { connectHttp, type HttpTransportHandle } from './http'
+
+let bridge: SceneBridge
+let server: McpServer
+let handle: HttpTransportHandle | null = null
+
+beforeEach(() => {
+  bridge = new SceneBridge()
+  bridge.loadDefault()
+  server = createPascalMcpServer({ bridge })
+})
+
+afterEach(async () => {
+  if (handle) {
+    await handle.close()
+    handle = null
+  }
+})
+
+test('connectHttp listens on the given port and accepts MCP traffic', async () => {
+  // Port 0 → OS assigns an ephemeral port.
+  handle = await connectHttp(server, 0)
+  expect(handle.port).toBeGreaterThan(0)
+
+  const url = new URL(`http://127.0.0.1:${handle.port}/mcp`)
+  const clientTransport = new StreamableHTTPClientTransport(url)
+  const client = new Client({ name: 'http-test-client', version: '0.0.0' })
+
+  try {
+    await client.connect(clientTransport)
+    const tools = await client.listTools()
+    expect(Array.isArray(tools.tools)).toBe(true)
+  } finally {
+    await client.close()
+  }
+})
+
+test('connectHttp close() stops the server', async () => {
+  handle = await connectHttp(server, 0)
+  const port = handle.port
+  await handle.close()
+  handle = null
+
+  // A fresh fetch to the old port should fail (connection refused).
+  let didConnect = false
+  try {
+    await fetch(`http://127.0.0.1:${port}/mcp`, {
+      method: 'POST',
+      headers: { 'content-type': 'application/json' },
+      body: '{}',
+      signal: AbortSignal.timeout(500),
+    })
+    didConnect = true
+  } catch {
+    didConnect = false
+  }
+  expect(didConnect).toBe(false)
+})