Current per-campaign poll map.
Fresh per-campaign poll map (may be undefined).
When true, incoming is the complete poll
list for every campaign it names; those campaigns are replaced
wholesale so deleted polls disappear. Defaults to false.
Merged map with polls preserved across ticks.
Merges two poll record maps by campaign ID, then by poll ID within each campaign. Incoming polls overwrite existing polls with the same ID so vote-count updates are always reflected, while polls absent from the incoming batch are preserved rather than silently dropped.