pub const V3_CHANNEL_TYPES: &[&str];Expand description
Channel section keys subject to V3 alias-wrapping. A missing entry
here sends its V2 [channels.<type>] block through the passthrough
branch, which leaves it flat instead of <type>.default-shaped and
the V3 deserializer then chokes on the typed HashMap<String, T>
slot. Tests cross-check this list against the typed channel slots
on ChannelsConfig to catch silent drift.