Two OCR-install fixes surfaced while verifying the accurate-OCR (v3 runtime) path end to end:
- Installer timeout must be a safe integer, not a performance.now() float. With the default INSTALL_MAX_MS this failed every accurate-OCR install via the app right after the download (masked by the unpublished runtime; CI drives install_runtime.py directly so it never surfaced). Fixed via remainingInstallerTimeoutMs().
- Classify an absent or forbidden runtime index (401/403/404/410) as OcrRuntimeNotPublishedError with a clear "Fast OCR still works" message instead of a raw HTTP 404, without retrying.
Refs #552
Defer the overall deadline until the first fetch is dispatched (the deferred-deadline pattern the sibling 20ms test already uses), so a loaded CI runner cannot abort before fetch and randomly fail Unit Tests.
