Pulls the trigger/poll/check-status state out of documents/[id]/+page.svelte
into a pure factory in lib/ocr/useOcrJob.svelte.ts that takes documentId,
fetchImpl, and onJobFinished callback as injected dependencies.
The page now delegates to ocrJob.triggerOcr / ocrJob.checkStatus /
ocrJob.destroy and reads ocrJob.running / .progressMessage / .errorMessage /
.skippedPages reactively.
Test discipline reset: 22 unit tests cover initial state, triggerOcr 200/
4xx-with-code/4xx-without-code/5xx/network-error paths, useExistingAnnotations
flag round-trip, checkStatus PENDING/RUNNING/DONE/no-jobId/empty-id/5xx/network
paths, polling progressMessage / skippedPages updates, DONE/FAILED → onJobFinished
callback, polling-error swallow, and destroy mid-poll cleanup.
Refs #496.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
