Create workspace

Create a new Docsbook documentation site (workspace) — the FIRST call for 'make a docs site', 'set up documentation', «сделай документацию». Idempotent: a repository that already has a workspace is returned with already_existed: true, so no lookup is needed first. Pages come next: write_docs, which takes MANY files in one call, so a whole first site lands as one commit. GITHUB IS OPTIONAL — this is the tool for BOTH cases: • From scratch, no GitHub at all: OMIT repo_full_name. Docsbook creates and hosts the documentation repository itself, under its own GitHub organisation, with its own credentials. The user needs no GitHub account, no connected GitHub app and no repository — never tell them to connect GitHub or bring a repo for this. Then call write_docs to publish the pages you wrote. • From the user's OWN repository: pass repo_full_name ('owner/repo'). Use this ONLY when they point at a repository of THEIRS — including the git remote of the checkout they are working in, which counts as pointing at it. It is what the site READS and what its public address is made of, so it must exist on GitHub and it must belong to this Docsbook account. Never pass somebody else's repository — a competitor's, a prospect's, an open-source project you are only reading: naming one does not create documentation from it, it would claim their name on a public Docsbook address. A repository this account has no claim on, or that GitHub does not have, is created as a Docsbook-hosted site instead, and the result then reports a different repo_full_name than you asked for, with a note saying so. If a workspace for this repo already exists, returns the existing one (already_existed: true). ALWAYS give the user site_url from the result verbatim; never build a link out of a GitHub username or repo name.