Finish a draft into a locked version.

The editor's Finalize, through its core, in two steps. Without coverage: Slug's judgment of whether the last passing coverage can be carried onto this version (status: judged, carryover), and nothing is locked. With coverage: adopt: that report is copied onto the version, the draft is locked and the screenplay is parsed and its characters analysed (refused with 409 script_state_invalid when no earlier version has passing coverage, before anything is locked). With coverage: fresh: the draft is locked and new coverage runs; the screenplay is parsed free, while character extraction, casting, voices and the table read wait until its coverage meets the target — refused with 409 project_precondition_failed while the project gate holds paid work. A version that is not a draft is refused with 409 script_state_invalid. Requires Idempotency-Key.