fix: explicitly set DISPLAY env var for Tauri binary on Linux

Diagnostics revealed that the DISPLAY environment variable was not
being propagated from the xvfb-run wrapper through ChromeDriver to
the Tauri binary, causing GTK to fail with "cannot open display" errors.

This commit adds explicit DISPLAY environment variable configuration
in Chrome options, ensuring the Tauri binary can access the X server
when running in CI environments with xvfb.

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

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

Author: goosewobbler

packages/tauri-service/src/launcher.ts

@@ -107,14 +107,23 @@ export default class TauriLaunchService {
       }
 
       // Set up Chrome options to use the Tauri app binary
+      // On Linux, ensure DISPLAY is set for xvfb
+      const env: Record<string, string> = {};
+      if (process.platform === 'linux') {
+        // Use DISPLAY from environment if set, otherwise default to :99
+        env.DISPLAY = process.env.DISPLAY || ':99';
+        log.info(`Setting DISPLAY=${env.DISPLAY} for Tauri binary`);
+      }
+
       cap['goog:chromeOptions'] = {
         binary: appBinaryPath,
         args: chromeArgs,
+        ...(Object.keys(env).length > 0 && { env }),
         prefs: {
           'profile.password_manager_leak_detection': false,
           'profile.default_content_setting_values.notifications': 2,
         },
-      };
+      } as (typeof cap)['goog:chromeOptions'] & { env?: Record<string, string> };
 
       // Disable WebDriver Bidi session
       cap['wdio:enforceWebDriverClassic'] = true;