test(cli): add integration coverage for wp liveblog fix-archive

[faisalahammad]

Summary

fix-archive had zero automated test coverage. Adds it, in the existing legacy style.
Refs #789

Investigation on #789

The issue asked for two things: drop the obsolete readme_for_github command, and refactor fix-archive into a namespaced command + service class with DI and behat tests.

• readme_for_github is already gone — removed on develop in 5becaad (PR Restructure documentation around audience #872), the same change that dropped readme.txt in favor of a WordPress.org-compatible README.md. Nothing to do there.
• The DDD refactor the issue describes already exists, but only on the 2.x branch (commit e760e10: FixArchiveCommand + ArchiveRepairService under src/php/, with DI and unit tests). develop is still the flat, legacy static-class style, and per project convention 2.x patterns are backported by hand when needed, not ported wholesale. Not doing that here.
• Checked whether the corruption fix-archive repairs (broken liveblog_replaces commentmeta + duplicated content after editing an entry twice) is still reachable. PR users can edit more than 1x now and reloaded page will show #297 already closed the supported REST/AJAX path by canonicalizing entry_id through replaces before it reaches the client. But validate_entry_belongs_to_post() still doesn't reject an entry_id that is itself an already-replaced ghost comment, so the same corruption stays reachable in principle (stale cached page, direct API caller, future regression). Recommend keeping fix-archive, not deprecating it.

So the only real gap left under this issue is missing test coverage, which this PR adds.

Changes

tests/Integration/wp-cli-stub.php (new)

Minimal WP_CLI/WP_CLI_Command stub (log, success, colorize, add_command), guarded by class_exists(). Needed because the real WP-CLI runtime isn't loaded under PHPUnit, and class-wpcom-liveblog-wp-cli.php calls WP_CLI::add_command() at file-load time plus WP_CLI::log()/::success()/::colorize() inside fix_archive().

tests/Integration/WpCliFixArchiveTest.php (new)

Extends the same Yoast\WPTestUtils\WPIntegration\TestCase base as EntryQueryTest.php. Covers:

• dry run (--dryrun) does not modify liveblog_replaces meta
• actual run corrects a mis-pointed liveblog_replaces value
• no liveblogs at all completes cleanly
• a liveblog with no edited entries completes cleanly

Testing

Test 1: PHPCS

1. composer cs
   Result: clean on both new files

Test 2: Lint

1. composer lint
   Result: no syntax errors

Test 3: CodeRabbit

1. coderabbit review --agent
   Result: 0 findings

Test 4: composer test:integration
Couldn't get a clean local wp-env run to verify this locally — repeated transient network failures during the WordPress core git clone / Alpine package install in the wp-env Docker build on this machine, unrelated to this change. Would appreciate a CI run or a maintainer re-run locally to confirm the four new test cases pass.