feat: default to headed mode across all platforms

- Change default headless setting from platform-dependent to false
- Browser now shows GUI windows by default on all platforms
- --headless flag still overrides to enable headless mode when needed
- Provides better user experience with visible browser interactions

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

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

src/config.ts

@@ -55,7 +55,7 @@ const defaultConfig: FullConfig = {
     browserName: 'chromium',
     launchOptions: {
       channel: 'chrome',
-      headless: os.platform() === 'linux' && !process.env.DISPLAY,
+      headless: false,
       chromiumSandbox: true,
     },
     contextOptions: {