`municipality.engagementLevel` (staff-only, no default) records what the
campaign decided to invest in a município, next to the E8/E10 metrics that
describe what it knows. Moving it is a reallocation decision, so only
unrestricted staff may, every move carries a rationale plus the signals that
would reverse it, and the write files an `allocationDecision` in the same
transaction under an advisory lock taken before the current level is read —
otherwise the snapshot's `from` is a guess. The enum gains `movimento`: a level
move is neither `aceita` nor `descarta`.
No backfill. Null is "Sem nível", and filtering by it is the triage queue.
That is also why the list sorts `nivel` in memory rather than in the query:
Postgres puts NULLs first on DESC, so a native sort would open "N4 primeiro"
on a page of municípios nobody has decided about yet. The filter stays native.
The hysteresis rules from research §6.8 are pure and client-safe, so the
Popover explains a block before submitting and the server re-runs them anyway;
a blocked move answers 409 with typed violations and the override is recorded
with exactly the rules it contradicted.
