Now that the OCR tool supports Transkribus (T326389), it can be added as an option to the on-wiki UI (that's part of the Wikisource extension).
- It should appear as a radio button alongside Tesseract and Google.
- Only some languages are available (T331960 will add more) so the option should only be made available for a specific set of Wikisources. This list will be a config variable which maps a wiki's ID to a (single) Transkribus model name (e.g. dewikisource → german-kurrent-and-sutterlin-17th-20th-century).
For now, there will only be a single model available for each wiki, but after T279405 we'll be able to extend this to support different ones.