chore: update CI configuration and enhance test stability

- Added deterministic API key and environment variables in e2e-tests.yml to ensure consistent test behavior.
- Refactored CodexProvider tests to improve type safety and mock handling, ensuring reliable test execution.
- Updated provider-factory tests to mock installation detection for CodexProvider, enhancing test isolation.
- Adjusted Playwright configuration to conditionally use external backend, improving flexibility in test environments.
- Enhanced kill-test-servers script to handle external server scenarios, ensuring proper cleanup of test processes.

These changes improve the reliability and maintainability of the testing framework, leading to a more stable development experience.

apps/ui/tests/utils/project/setup.ts

@@ -6,7 +6,7 @@ import { Page } from '@playwright/test';
  */
 const STORE_VERSIONS = {
   APP_STORE: 2, // Must match app-store.ts persist version
-  SETUP_STORE: 0, // setup-store.ts doesn't specify a version, so zustand defaults to 0
+  SETUP_STORE: 1, // Must match setup-store.ts persist version
 } as const;
 
 /**
@@ -56,6 +56,7 @@ export async function setupWelcomeView(
           currentView: 'welcome',
           theme: 'dark',
           sidebarOpen: true,
+          skipSandboxWarning: true,
           apiKeys: { anthropic: '', google: '' },
           chatSessions: [],
           chatHistoryOpen: false,
@@ -135,6 +136,7 @@ export async function setupRealProject(
           currentView: currentProject ? 'board' : 'welcome',
           theme: 'dark',
           sidebarOpen: true,
+          skipSandboxWarning: true,
           apiKeys: { anthropic: '', google: '' },
           chatSessions: [],
           chatHistoryOpen: false,