[feat] remove backward compatibility endpoints

@choinek you generally just convinced me (after I've analyzed it for a while with the latest release) that keeping the backward compatibility forever is waste of energy and resources.

After we add the `extract` endpoint - let's keep the `ocr` endpoints as deprecated until the end of February max. Then, let's remove it.

Start by locating the deprecated `ocr` endpoints and the newer `extract` endpoint in the repository, then review how endpoint removal is tested or documented. Confirm that `extract` is available before removing the backward-compatibility endpoints; done means the `ocr` endpoints are no longer exposed and existing supported behavior remains covered.

Written by the indexing model from the issue text.