Per-export CDC settings, required when mode: cdc. The output table,
destination, and format come from the export itself; this carries only the
CDC-specific knobs (resume + per-engine stream params).
Calendar bucket width for date/timestamp output partitioning
(ExportConfig::partition_by). The partition column must be a DATE or
TIMESTAMP column; this picks how its range is split into contiguous Hive
buckets. It is not a knob for partitioning by arbitrary column values.
Operational environment of the source database — drives the default tuning
profile when none is explicitly set. Opt-in: existing configs without
environment: continue to use balanced as today.
Default PostgreSQL logical slot when cdc.slot is omitted — shared by the
runner (crate::pipeline’s cdc job) and config validation, so the
same-slot conflict check sees the value that will actually be used.
L24: when a compression_profile is set and the user also wrote an
explicit codec the profile silently discards, return a one-line warning
naming both — otherwise None.