Masked email: the fork's subspace and the masked_email module (ME-1, ME-2, ME-3, ME-6a, ME-7, ME-8, ME-13, ME-14, ME-15)

Subspace _ holds the fork's own data, with its own SQL table and RocksDB
column family, and is part of backup. The masked_email module keeps each
mask's state, last mail and pending deadline beside upstream's record, an
index from address to mask with tombstones, and a per-account change log;
and generates addresses in the fork's format.

crates/common/src/manager/backup.rs

@@ -321,6 +321,7 @@ impl Family {
                 SUBSPACE_REGISTRY_IDX,
                 SUBSPACE_REGISTRY_PK,
                 SUBSPACE_DIRECTORY,
+                store::SUBSPACE_INBUXA, // inbuxa: masked email
             ],
             Family::Changelog => &[SUBSPACE_LOGS],
             Family::Queue => &[SUBSPACE_QUEUE_MESSAGE, SUBSPACE_QUEUE_EVENT],