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/features/src/masked_email/mod.rs

@@ -0,0 +1,22 @@
+/*
+ * SPDX-FileCopyrightText: 2026 Coffey Labs
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+//! Masked email, built from `docs/spec/features/masked-email.md`.
+//!
+//! A masked address is a disposable address that delivers to one account.
+//! Upstream's `x:MaskedEmail` record stays exactly as upstream writes it. What
+//! the fork adds (the one state both APIs share, when mail last arrived, the
+//! address index delivery uses, tombstones and the change log) lives beside
+//! it in the fork's own subspace (`data`). Requirements are named `ME-n`,
+//! after the spec.
+
+pub mod address;
+pub mod data;
+pub mod ops;
+pub mod policy;
+pub mod state;
+
+pub use state::State;