fix(ServerManager): replace hardcoded sleep(1) with polling loop (#155)

[s2x]

Summary

• Replace sleep(1) in ServerManager::getStatus() with a polling loop that checks every 50ms for the status file
• Add status_timeout config option (default 5s) to make the timeout configurable (follows stop_timeout pattern)
• Extract waitForFile() and getStatusTimeout() private methods for clean separation
• Add 5 unit tests covering: existing file, timeout, file-appears-during-polling, default config, custom config

Test Plan

• composer test — 334 tests, 1016 assertions, 0 failures (1 pre-existing HttpRequestHandlerTest error unrelated to this change)
• composer lint — CS fixer, phpstan, rector all pass

Closes #155