test: run tests on MCP server inside Docker (#361)

https://github.com/microsoft/playwright-mcp/issues/346

tests/headed.spec.ts

@@ -20,6 +20,7 @@ for (const mcpHeadless of [false, true]) {
   test.describe(`mcpHeadless: ${mcpHeadless}`, () => {
     test.use({ mcpHeadless });
     test.skip(process.platform === 'linux', 'Auto-detection wont let this test run on linux');
+    test.skip(({ mcpMode, mcpHeadless }) => mcpMode === 'docker' && !mcpHeadless, 'Headed mode is not supported in docker');
     test('browser', async ({ client, server, mcpBrowser }) => {
       test.skip(!['chrome', 'msedge', 'chromium'].includes(mcpBrowser ?? ''), 'Only chrome is supported for this test');
       server.route('/', (req, res) => {