Redefine label review lifecycle to cover extraction and compliance

# Context

`ReviewStatus` (`not_started` / `in_progress` / `completed`) was modelled before compliance checks existed. It now conflates extraction, human data review, and compliance evaluation into one opaque field, and the user cannot tell from any given label where it is in the workflow or what action is theirs to take.

# Outcome

An agreed vocabulary and state model for a label's lifecycle that covers extraction, compliance evaluation, and human review, and maps cleanly onto what the user sees.

# Acceptance criteria

- Every stage a label can be in is named and defined
- Every transition between stages is defined, including its trigger (automatic vs. user-driven) and preconditions
- The meaning of "review" is unambiguous once compliance exists
- The model defines what happens to compliance verdicts when extracted data is edited after evaluation
- The model defines what "done" means for a label and what is required to reach it
- The model defines who can advance a label between stages, or explicitly defers that question
- The UI representation is defined: a user opening a label can tell at a glance what stage it is in and what action is expected of them
- Existing terminology inconsistencies between backend enums, API, and UI strings are resolved