Add frontend unit tests for dorc-web components

Background

The dorc-web project has no unit test infrastructure. All UI behavior is manually tested. PR #584 added significant UI logic (source control type icons, combo-box binding, conditional field visibility) that would benefit from automated tests.

Current State

• No test framework configured ("test": "echo no test specified")
• Only k6 load tests exist (k6-tests/) which test API performance, not UI logic
• page-test-component.ts exists but is a development helper, not a test

Recommended Approach

1. Add Vitest (works with Vite out of the box) + @open-wc/testing for Lit component testing
2. Priority components to test:
   • add-edit-project.ts — source control type combo-box binding, conditional field visibility (showSubPaths/showBuildRegex), label switching per type
   • page-projects-list.ts — source control icon renderer (AzDO/GitHub/FileShare detection), project name tooltip, search filtering
   • project-controls.ts — button visibility based on permissions
   • deploy-env.ts — build definition handling, folder project detection
3. Test the enum string serialization edge case (API returns "FileShare" not 2)

Setup Steps

npm install -D vitest @open-wc/testing @testing-library/dom jsdom

Add to vite.config.ts:

test: {
  environment: 'jsdom',
  include: ['src/**/*.test.ts']
}

Identified during PR #584 UI development