Remove hard-coded halos.local references from E2E tests

[mairas]

Overview

Remove hard-coded halos.local hostname references from E2E test files to comply with the workspace hostname policy.

Tracking issue: hatlabs/halos-distro#61

Violations

Multiple E2E test files have hard-coded URLs:

• compare-layouts.js
• frontend/playwright.config.ts
• frontend/test/e2e/simple-screenshot.mjs
• frontend/test/e2e/test-css-loading.mjs
• inspect-html.js
• test-dark-theme.js
• test-fresh.js
• test-layout.js
• test-storage-layout.js
• test-tabs.js

Fix

1. playwright.config.ts: Read baseURL from environment variable HALOS_TEST_URL
2. All test files: Use the configured baseURL from Playwright config or read from environment

Example fix for playwright.config.ts:

export default defineConfig({
  use: {
    baseURL: process.env.HALOS_TEST_URL || 'https://localhost:9090',
  },
});

Enforcement

A pre-commit hook has been added. Run .github/scripts/check-hardcoded-hostnames.sh to verify.